diff --git a/.editorconfig b/.editorconfig
index 32314fd23..09294cd3e 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -128,6 +128,24 @@ dotnet_diagnostic.CA1822.severity = suggestion
 # IDE0080: Remove unnecessary suppression operator
 dotnet_diagnostic.IDE0080.severity = error
 
+# CA1716: Rename namespace "" so that it no longer conflicts with the reserved language keyword 'Interface'
+# TODO: fixing this would be breaking
+dotnet_diagnostic.CA1716.severity = suggestion
+
+# CA1805: Do not initialize unnecessarily
+dotnet_diagnostic.CA1805.severity = suggestion
+
+# CA1711: Identifiers should not have incorrect suffix
+# TODO: fixing this would be breaking
+dotnet_diagnostic.CA1711.severity = suggestion
+
+# CA2201: Do not raise reserved exception types
+dotnet_diagnostic.CA2201.severity = suggestion
+
+# CA1720: Identifier contains type name
+# TODO: fixing this would be breaking
+dotnet_diagnostic.CA1720.severity = suggestion
+
 [Program.cs]
 dotnet_diagnostic.CA1050.severity = none
 dotnet_diagnostic.S1118.severity = none
diff --git a/src/Altinn.App.Api/Controllers/ApplicationMetadataController.cs b/src/Altinn.App.Api/Controllers/ApplicationMetadataController.cs
index 02d86b06e..386d4c714 100644
--- a/src/Altinn.App.Api/Controllers/ApplicationMetadataController.cs
+++ b/src/Altinn.App.Api/Controllers/ApplicationMetadataController.cs
@@ -47,7 +47,7 @@ public async Task<ActionResult<ApplicationMetadata>> GetAction(
 
         string wantedAppId = $"{org}/{app}";
 
-        if (!checkOrgApp || application.Id.Equals(wantedAppId))
+        if (!checkOrgApp || application.Id.Equals(wantedAppId, StringComparison.Ordinal))
         {
             return Ok(application);
         }
@@ -72,7 +72,7 @@ public async Task<ActionResult<string>> GetPolicy(string org, string app)
             string policy = await _appMetadata.GetApplicationXACMLPolicy();
             string wantedAppId = $"{org}/{app}";
 
-            if (application.Id.Equals(wantedAppId))
+            if (application.Id.Equals(wantedAppId, StringComparison.Ordinal))
             {
                 return Content(policy, "text/xml", System.Text.Encoding.UTF8);
             }
@@ -100,7 +100,7 @@ public async Task<ActionResult<string>> GetProcess(string org, string app)
         string wantedAppId = $"{org}/{app}";
         try
         {
-            if (application.Id.Equals(wantedAppId))
+            if (application.Id.Equals(wantedAppId, StringComparison.Ordinal))
             {
                 string process = await _appMetadata.GetApplicationBPMNProcess();
                 return Content(process, "text/xml", System.Text.Encoding.UTF8);
diff --git a/src/Altinn.App.Api/Controllers/AuthorizationController.cs b/src/Altinn.App.Api/Controllers/AuthorizationController.cs
index 13f4e04cc..7590e0dfc 100644
--- a/src/Altinn.App.Api/Controllers/AuthorizationController.cs
+++ b/src/Altinn.App.Api/Controllers/AuthorizationController.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using Altinn.App.Core.Configuration;
 using Altinn.App.Core.Helpers;
 using Altinn.App.Core.Internal.Auth;
@@ -83,7 +84,7 @@ public async Task<ActionResult> GetCurrentParty(bool returnPartyObject = false)
         {
             Response.Cookies.Append(
                 _settings.GetAltinnPartyCookieName,
-                userContext.PartyId.ToString(),
+                userContext.PartyId.ToString(CultureInfo.InvariantCulture),
                 new CookieOptions { Domain = _settings.HostName }
             );
         }
diff --git a/src/Altinn.App.Api/Controllers/DataController.cs b/src/Altinn.App.Api/Controllers/DataController.cs
index 4f51ea025..fe709a6e9 100644
--- a/src/Altinn.App.Api/Controllers/DataController.cs
+++ b/src/Altinn.App.Api/Controllers/DataController.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Net;
 using System.Security.Claims;
 using System.Text.Json;
@@ -133,7 +134,7 @@ [FromQuery] string dataType
             Application application = await _appMetadata.GetApplicationMetadata();
 
             DataType? dataTypeFromMetadata = application.DataTypes.First(e =>
-                e.Id.Equals(dataType, StringComparison.InvariantCultureIgnoreCase)
+                e.Id.Equals(dataType, StringComparison.OrdinalIgnoreCase)
             );
 
             if (dataTypeFromMetadata == null)
@@ -302,7 +303,9 @@ public async Task<ActionResult> Get(
                 return NotFound($"Did not find instance {instance}");
             }
 
-            DataElement? dataElement = instance.Data.First(m => m.Id.Equals(dataGuid.ToString()));
+            DataElement? dataElement = instance.Data.First(m =>
+                m.Id.Equals(dataGuid.ToString(), StringComparison.Ordinal)
+            );
 
             if (dataElement == null)
             {
@@ -380,7 +383,9 @@ public async Task<ActionResult> Put(
                 );
             }
 
-            DataElement? dataElement = instance.Data.First(m => m.Id.Equals(dataGuid.ToString()));
+            DataElement? dataElement = instance.Data.First(m =>
+                m.Id.Equals(dataGuid.ToString(), StringComparison.Ordinal)
+            );
 
             if (dataElement == null)
             {
@@ -459,7 +464,7 @@ public async Task<ActionResult<DataPatchResponse>> PatchFormData(
                 );
             }
 
-            var dataElement = instance.Data.First(m => m.Id.Equals(dataGuid.ToString()));
+            var dataElement = instance.Data.First(m => m.Id.Equals(dataGuid.ToString(), StringComparison.Ordinal));
 
             if (dataElement == null)
             {
@@ -547,7 +552,9 @@ [FromRoute] Guid dataGuid
                 );
             }
 
-            DataElement? dataElement = instance.Data.Find(m => m.Id.Equals(dataGuid.ToString()));
+            DataElement? dataElement = instance.Data.Find(m =>
+                m.Id.Equals(dataGuid.ToString(), StringComparison.Ordinal)
+            );
 
             if (dataElement == null)
             {
@@ -604,7 +611,7 @@ private async Task<ActionResult> CreateBinaryData(
         Stream fileStream
     )
     {
-        int instanceOwnerPartyId = int.Parse(instanceBefore.Id.Split("/")[0]);
+        int instanceOwnerPartyId = int.Parse(instanceBefore.Id.Split("/")[0], CultureInfo.InvariantCulture);
         Guid instanceGuid = Guid.Parse(instanceBefore.Id.Split("/")[1]);
 
         DataElement dataElement = await _dataClient.InsertBinaryData(
@@ -655,7 +662,7 @@ private async Task<ActionResult> CreateAppModelData(string org, string app, Inst
         await UpdatePresentationTextsOnInstance(instance, dataType, appModel);
         await UpdateDataValuesOnInstance(instance, dataType, appModel);
 
-        int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId);
+        int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId, CultureInfo.InvariantCulture);
 
         ObjectUtils.InitializeAltinnRowId(appModel);
         ObjectUtils.PrepareModelForXmlStorage(appModel);
@@ -692,7 +699,7 @@ DataElement dataElement
         if (dataStream != null)
         {
             string? userOrgClaim = User.GetOrg();
-            if (userOrgClaim == null || !org.Equals(userOrgClaim, StringComparison.InvariantCultureIgnoreCase))
+            if (userOrgClaim == null || !org.Equals(userOrgClaim, StringComparison.OrdinalIgnoreCase))
             {
                 await _instanceClient.UpdateReadStatus(instanceOwnerPartyId, instanceGuid, "read");
             }
@@ -822,7 +829,7 @@ await _dataClient.UpdateData(
 
         // This is likely not required as the instance is already read
         string? userOrgClaim = User.GetOrg();
-        if (userOrgClaim == null || !org.Equals(userOrgClaim, StringComparison.InvariantCultureIgnoreCase))
+        if (userOrgClaim == null || !org.Equals(userOrgClaim, StringComparison.OrdinalIgnoreCase))
         {
             await _instanceClient.UpdateReadStatus(instanceOwnerId, instanceGuid, "read");
         }
@@ -860,7 +867,7 @@ private async Task<ActionResult> PutFormData(
         string? language
     )
     {
-        int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId);
+        int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId, CultureInfo.InvariantCulture);
 
         string classRef = dataType.AppLogic.ClassRef;
         Guid instanceGuid = Guid.Parse(instance.Id.Split("/")[1]);
@@ -928,7 +935,7 @@ private async Task UpdatePresentationTextsOnInstance(Instance instance, string d
         if (updatedValues.Count > 0)
         {
             await _instanceClient.UpdatePresentationTexts(
-                int.Parse(instance.Id.Split("/")[0]),
+                int.Parse(instance.Id.Split("/")[0], CultureInfo.InvariantCulture),
                 Guid.Parse(instance.Id.Split("/")[1]),
                 new PresentationTexts { Texts = updatedValues }
             );
@@ -947,7 +954,7 @@ private async Task UpdateDataValuesOnInstance(Instance instance, string dataType
         if (updatedValues.Count > 0)
         {
             await _instanceClient.UpdateDataValues(
-                int.Parse(instance.Id.Split("/")[0]),
+                int.Parse(instance.Id.Split("/")[0], CultureInfo.InvariantCulture),
                 Guid.Parse(instance.Id.Split("/")[1]),
                 new DataValues { Values = updatedValues }
             );
@@ -996,7 +1003,7 @@ private static bool IsValidContributer(DataType dataType, ClaimsPrincipal user)
             string key = item.Split(':')[0];
             string value = item.Split(':')[1];
 
-            switch (key.ToLower())
+            switch (key.ToLowerInvariant())
             {
                 case "org":
                     if (value.Equals(user.GetOrg(), StringComparison.OrdinalIgnoreCase))
@@ -1006,7 +1013,12 @@ private static bool IsValidContributer(DataType dataType, ClaimsPrincipal user)
 
                     break;
                 case "orgno":
-                    if (value.Equals(user.GetOrgNumber().ToString()))
+                    if (
+                        value.Equals(
+                            user.GetOrgNumber()?.ToString(CultureInfo.InvariantCulture),
+                            StringComparison.Ordinal
+                        )
+                    )
                     {
                         return true;
                     }
diff --git a/src/Altinn.App.Api/Controllers/DataTagsController.cs b/src/Altinn.App.Api/Controllers/DataTagsController.cs
index 9b9116984..1a13dc698 100644
--- a/src/Altinn.App.Api/Controllers/DataTagsController.cs
+++ b/src/Altinn.App.Api/Controllers/DataTagsController.cs
@@ -61,7 +61,9 @@ [FromRoute] Guid dataGuid
             return NotFound($"Unable to find instance based on the given parameters.");
         }
 
-        DataElement? dataElement = instance.Data.FirstOrDefault(m => m.Id.Equals(dataGuid.ToString()));
+        DataElement? dataElement = instance.Data.FirstOrDefault(m =>
+            m.Id.Equals(dataGuid.ToString(), StringComparison.Ordinal)
+        );
 
         if (dataElement == null)
         {
@@ -106,7 +108,9 @@ [FromBody] string tag
             return NotFound("Unable to find instance based on the given parameters.");
         }
 
-        DataElement? dataElement = instance.Data.FirstOrDefault(m => m.Id.Equals(dataGuid.ToString()));
+        DataElement? dataElement = instance.Data.FirstOrDefault(m =>
+            m.Id.Equals(dataGuid.ToString(), StringComparison.Ordinal)
+        );
 
         if (dataElement == null)
         {
@@ -160,7 +164,9 @@ [FromRoute] string tag
             return NotFound("Unable to find instance based on the given parameters.");
         }
 
-        DataElement? dataElement = instance.Data.FirstOrDefault(m => m.Id.Equals(dataGuid.ToString()));
+        DataElement? dataElement = instance.Data.FirstOrDefault(m =>
+            m.Id.Equals(dataGuid.ToString(), StringComparison.Ordinal)
+        );
 
         if (dataElement == null)
         {
diff --git a/src/Altinn.App.Api/Controllers/InstancesController.cs b/src/Altinn.App.Api/Controllers/InstancesController.cs
index cdf5651c9..66aa24586 100644
--- a/src/Altinn.App.Api/Controllers/InstancesController.cs
+++ b/src/Altinn.App.Api/Controllers/InstancesController.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Net;
 using System.Text;
 using Altinn.App.Api.Helpers.RequestHandling;
@@ -146,7 +147,7 @@ [FromRoute] Guid instanceGuid
 
             string? userOrgClaim = User.GetOrg();
 
-            if (userOrgClaim == null || !org.Equals(userOrgClaim, StringComparison.InvariantCultureIgnoreCase))
+            if (userOrgClaim == null || !org.Equals(userOrgClaim, StringComparison.OrdinalIgnoreCase))
             {
                 await _instanceClient.UpdateReadStatus(instanceOwnerPartyId, instanceGuid, "read");
             }
@@ -239,7 +240,10 @@ [FromQuery] int? instanceOwnerPartyId
             // create minimum instance template
             instanceTemplate = new Instance
             {
-                InstanceOwner = new InstanceOwner { PartyId = instanceOwnerPartyId.Value.ToString() }
+                InstanceOwner = new InstanceOwner
+                {
+                    PartyId = instanceOwnerPartyId.Value.ToString(CultureInfo.InvariantCulture)
+                }
             };
         }
 
@@ -331,7 +335,7 @@ [FromQuery] int? instanceOwnerPartyId
             instance = await _instanceClient.GetInstance(
                 app,
                 org,
-                int.Parse(instance.InstanceOwner.PartyId),
+                int.Parse(instance.InstanceOwner.PartyId, CultureInfo.InvariantCulture),
                 Guid.Parse(instance.Id.Split("/")[1])
             );
 
@@ -425,7 +429,11 @@ [FromBody] InstansiationInstance instansiationInstance
             return NotFound($"Cannot lookup party: {partyLookupException.Message}");
         }
 
-        if (copySourceInstance && party.PartyId.ToString() != instansiationInstance.SourceInstanceId.Split("/")[0])
+        if (
+            copySourceInstance
+            && party.PartyId.ToString(CultureInfo.InvariantCulture)
+                != instansiationInstance.SourceInstanceId.Split("/")[0]
+        )
         {
             return BadRequest("It is not possible to copy instances between instance owners.");
         }
@@ -705,7 +713,7 @@ [FromBody] Substatus substatus
         Instance instance = await _instanceClient.GetInstance(app, org, instanceOwnerPartyId, instanceGuid);
 
         string? orgClaim = User.GetOrg();
-        if (!instance.Org.Equals(orgClaim))
+        if (!instance.Org.Equals(orgClaim, StringComparison.OrdinalIgnoreCase))
         {
             return Forbid();
         }
@@ -783,7 +791,7 @@ int instanceOwnerPartyId
             new()
             {
                 { "appId", $"{org}/{app}" },
-                { "instanceOwner.partyId", instanceOwnerPartyId.ToString() },
+                { "instanceOwner.partyId", instanceOwnerPartyId.ToString(CultureInfo.InvariantCulture) },
                 { "status.isArchived", "false" },
                 { "status.isSoftDeleted", "false" }
             };
@@ -863,14 +871,17 @@ Instance sourceInstance
     {
         string org = application.Org;
         string app = application.AppIdentifier.App;
-        int instanceOwnerPartyId = int.Parse(targetInstance.InstanceOwner.PartyId);
+        int instanceOwnerPartyId = int.Parse(targetInstance.InstanceOwner.PartyId, CultureInfo.InvariantCulture);
 
         string[] sourceSplit = sourceInstance.Id.Split("/");
         Guid sourceInstanceGuid = Guid.Parse(sourceSplit[1]);
 
         List<DataType> dts = application
             .DataTypes.Where(dt => dt.AppLogic?.ClassRef != null)
-            .Where(dt => dt.TaskId != null && dt.TaskId.Equals(targetInstance.Process.CurrentTask.ElementId))
+            .Where(dt =>
+                dt.TaskId != null
+                && dt.TaskId.Equals(targetInstance.Process.CurrentTask.ElementId, StringComparison.Ordinal)
+            )
             .ToList();
         List<string> excludedDataTypes = application.CopyInstanceSettings.ExcludedDataTypes;
 
@@ -881,9 +892,9 @@ Instance sourceInstance
                 continue;
             }
 
-            if (dts.Any(dts => dts.Id.Equals(de.DataType)))
+            if (dts.Any(dts => dts.Id.Equals(de.DataType, StringComparison.Ordinal)))
             {
-                DataType dt = dts.First(dt => dt.Id.Equals(de.DataType));
+                DataType dt = dts.First(dt => dt.Id.Equals(de.DataType, StringComparison.Ordinal));
 
                 Type type;
                 try
@@ -913,7 +924,11 @@ Instance sourceInstance
                     DataHelper.ResetDataFields(application.CopyInstanceSettings.ExcludedDataFields, data);
                 }
 
-                await _prefillService.PrefillDataModel(instanceOwnerPartyId.ToString(), dt.Id, data);
+                await _prefillService.PrefillDataModel(
+                    instanceOwnerPartyId.ToString(CultureInfo.InvariantCulture),
+                    dt.Id,
+                    data
+                );
 
                 await _instantiationProcessor.DataCreation(targetInstance, data, null);
 
@@ -998,7 +1013,9 @@ string action
         {
             try
             {
-                return await _altinnPartyClientClient.GetParty(int.Parse(instanceOwner.PartyId));
+                return await _altinnPartyClientClient.GetParty(
+                    int.Parse(instanceOwner.PartyId, CultureInfo.InvariantCulture)
+                );
             }
             catch (Exception e) when (e is not ServiceException)
             {
@@ -1058,7 +1075,7 @@ string action
     private async Task StorePrefillParts(Instance instance, ApplicationMetadata appInfo, List<RequestPart> parts)
     {
         Guid instanceGuid = Guid.Parse(instance.Id.Split("/")[1]);
-        int instanceOwnerIdAsInt = int.Parse(instance.InstanceOwner.PartyId);
+        int instanceOwnerIdAsInt = int.Parse(instance.InstanceOwner.PartyId, CultureInfo.InvariantCulture);
         string org = instance.Org;
         string app = instance.AppId.Split("/")[1];
 
@@ -1219,7 +1236,7 @@ object data
         if (updatedValues.Count > 0)
         {
             await _instanceClient.UpdatePresentationTexts(
-                int.Parse(instance.Id.Split("/")[0]),
+                int.Parse(instance.Id.Split("/")[0], CultureInfo.InvariantCulture),
                 Guid.Parse(instance.Id.Split("/")[1]),
                 new PresentationTexts { Texts = updatedValues }
             );
@@ -1238,7 +1255,7 @@ object data
         if (updatedValues.Count > 0)
         {
             await _instanceClient.UpdateDataValues(
-                int.Parse(instance.Id.Split("/")[0]),
+                int.Parse(instance.Id.Split("/")[0], CultureInfo.InvariantCulture),
                 Guid.Parse(instance.Id.Split("/")[1]),
                 new DataValues { Values = updatedValues }
             );
diff --git a/src/Altinn.App.Api/Controllers/PartiesController.cs b/src/Altinn.App.Api/Controllers/PartiesController.cs
index 39ce416bb..0fe5ff7d9 100644
--- a/src/Altinn.App.Api/Controllers/PartiesController.cs
+++ b/src/Altinn.App.Api/Controllers/PartiesController.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using Altinn.App.Core.Configuration;
 using Altinn.App.Core.Helpers;
 using Altinn.App.Core.Internal.App;
@@ -167,7 +168,7 @@ public async Task<IActionResult> UpdateSelectedParty(int partyId)
 
         Response.Cookies.Append(
             _settings.GetAltinnPartyCookieName,
-            partyId.ToString(),
+            partyId.ToString(CultureInfo.InvariantCulture),
             new CookieOptions { Domain = _settings.HostName }
         );
 
diff --git a/src/Altinn.App.Api/Controllers/PdfController.cs b/src/Altinn.App.Api/Controllers/PdfController.cs
index 29434aabb..433849140 100644
--- a/src/Altinn.App.Api/Controllers/PdfController.cs
+++ b/src/Altinn.App.Api/Controllers/PdfController.cs
@@ -132,7 +132,7 @@ [FromRoute] Guid dataGuid
                 JsonSerializer.Deserialize<LayoutSets>(layoutSetsString, _jsonSerializerOptions)
                 ?? throw new JsonException("Could not deserialize LayoutSets");
             layoutSet = layoutSets.Sets?.FirstOrDefault(t =>
-                t.DataType.Equals(dataElement.DataType) && t.Tasks.Contains(taskId)
+                t.DataType.Equals(dataElement.DataType, StringComparison.Ordinal) && t.Tasks.Contains(taskId)
             );
         }
 
diff --git a/src/Altinn.App.Api/Controllers/ProcessController.cs b/src/Altinn.App.Api/Controllers/ProcessController.cs
index dc46a040f..5c5099b2b 100644
--- a/src/Altinn.App.Api/Controllers/ProcessController.cs
+++ b/src/Altinn.App.Api/Controllers/ProcessController.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Net;
 using Altinn.App.Api.Infrastructure.Filters;
 using Altinn.App.Api.Models;
@@ -563,7 +564,12 @@ [FromRoute] Guid instanceGuid
     {
         try
         {
-            return Ok(await _processClient.GetProcessHistory(instanceGuid.ToString(), instanceOwnerPartyId.ToString()));
+            return Ok(
+                await _processClient.GetProcessHistory(
+                    instanceGuid.ToString(),
+                    instanceOwnerPartyId.ToString(CultureInfo.InvariantCulture)
+                )
+            );
         }
         catch (PlatformHttpException e)
         {
diff --git a/src/Altinn.App.Api/Controllers/RedirectController.cs b/src/Altinn.App.Api/Controllers/RedirectController.cs
index e71dc4bc9..a93ca9bef 100644
--- a/src/Altinn.App.Api/Controllers/RedirectController.cs
+++ b/src/Altinn.App.Api/Controllers/RedirectController.cs
@@ -80,6 +80,6 @@ private bool IsValidRedirectUri(string urlHost)
             .ToList();
         string redirectHost = string.Join(".", goToList);
 
-        return validHost.Equals(redirectHost);
+        return validHost.Equals(redirectHost, StringComparison.OrdinalIgnoreCase);
     }
 }
diff --git a/src/Altinn.App.Api/Controllers/StatelessDataController.cs b/src/Altinn.App.Api/Controllers/StatelessDataController.cs
index 49df9bd01..7aaa0f322 100644
--- a/src/Altinn.App.Api/Controllers/StatelessDataController.cs
+++ b/src/Altinn.App.Api/Controllers/StatelessDataController.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Net;
 using Altinn.App.Api.Infrastructure.Filters;
 using Altinn.App.Core.Extensions;
@@ -110,7 +111,12 @@ public async Task<ActionResult> Get(
             );
         }
 
-        EnforcementResult enforcementResult = await AuthorizeAction(org, app, Convert.ToInt32(owner.PartyId), "read");
+        EnforcementResult enforcementResult = await AuthorizeAction(
+            org,
+            app,
+            Convert.ToInt32(owner.PartyId, CultureInfo.InvariantCulture),
+            "read"
+        );
 
         if (!enforcementResult.Authorized)
         {
@@ -225,7 +231,12 @@ public async Task<ActionResult> Post(
             return BadRequest($"Invalid party header");
         }
 
-        EnforcementResult enforcementResult = await AuthorizeAction(org, app, Convert.ToInt32(owner.PartyId), "read");
+        EnforcementResult enforcementResult = await AuthorizeAction(
+            org,
+            app,
+            Convert.ToInt32(owner.PartyId, CultureInfo.InvariantCulture),
+            "read"
+        );
 
         if (!enforcementResult.Authorized)
         {
diff --git a/src/Altinn.App.Api/Helpers/RequestHandling/MultipartRequestReader.cs b/src/Altinn.App.Api/Helpers/RequestHandling/MultipartRequestReader.cs
index a65a81bfa..9aa77216c 100644
--- a/src/Altinn.App.Api/Helpers/RequestHandling/MultipartRequestReader.cs
+++ b/src/Altinn.App.Api/Helpers/RequestHandling/MultipartRequestReader.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using Altinn.App.Core.Helpers.Extensions;
 using Microsoft.AspNetCore.WebUtilities;
 using Microsoft.Net.Http.Headers;
@@ -69,13 +70,25 @@ out ContentDispositionHeaderValue? contentDisposition
                         )
                     )
                     {
-                        Errors.Add(string.Format("Part number {0} doesn't have a content disposition", partCounter));
+                        Errors.Add(
+                            string.Format(
+                                CultureInfo.InvariantCulture,
+                                "Part number {0} doesn't have a content disposition",
+                                partCounter
+                            )
+                        );
                         continue;
                     }
 
                     if (section.ContentType == null)
                     {
-                        Errors.Add(string.Format("Part number {0} doesn't have a content type", partCounter));
+                        Errors.Add(
+                            string.Format(
+                                CultureInfo.InvariantCulture,
+                                "Part number {0} doesn't have a content type",
+                                partCounter
+                            )
+                        );
                         continue;
                     }
 
diff --git a/src/Altinn.App.Api/Helpers/RequestHandling/RequestPartValidator.cs b/src/Altinn.App.Api/Helpers/RequestHandling/RequestPartValidator.cs
index c52b919dd..ebe525264 100644
--- a/src/Altinn.App.Api/Helpers/RequestHandling/RequestPartValidator.cs
+++ b/src/Altinn.App.Api/Helpers/RequestHandling/RequestPartValidator.cs
@@ -27,7 +27,7 @@ public RequestPartValidator(Application appInfo)
     {
         if (part.Name == "instance")
         {
-            if (!part.ContentType.StartsWith("application/json"))
+            if (!part.ContentType.StartsWith("application/json", StringComparison.Ordinal))
             {
                 return $"Unexpected Content-Type '{part.ContentType}' of embedded instance template. Expecting 'application/json'";
             }
diff --git a/src/Altinn.App.Api/Infrastructure/Telemetry/HealthTelemetryFilter.cs b/src/Altinn.App.Api/Infrastructure/Telemetry/HealthTelemetryFilter.cs
index 5b87dd537..1859d8ffd 100644
--- a/src/Altinn.App.Api/Infrastructure/Telemetry/HealthTelemetryFilter.cs
+++ b/src/Altinn.App.Api/Infrastructure/Telemetry/HealthTelemetryFilter.cs
@@ -37,7 +37,7 @@ private static bool ExcludeItemTelemetry(ITelemetry item)
     {
         RequestTelemetry request = item as RequestTelemetry;
 
-        if (request != null && request.Url.ToString().EndsWith("/health"))
+        if (request != null && request.Url.ToString().EndsWith("/health", StringComparison.OrdinalIgnoreCase))
         {
             return true;
         }
diff --git a/src/Altinn.App.Api/Infrastructure/Telemetry/IdentityTelemetryFilter.cs b/src/Altinn.App.Api/Infrastructure/Telemetry/IdentityTelemetryFilter.cs
index f0eb983dc..15141dd86 100644
--- a/src/Altinn.App.Api/Infrastructure/Telemetry/IdentityTelemetryFilter.cs
+++ b/src/Altinn.App.Api/Infrastructure/Telemetry/IdentityTelemetryFilter.cs
@@ -1,5 +1,6 @@
 #nullable disable
 using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
 using Altinn.App.Core.Extensions;
 using Microsoft.ApplicationInsights.Channel;
 using Microsoft.ApplicationInsights.DataContracts;
@@ -42,17 +43,17 @@ public void Process(ITelemetry item)
                 int? partyId = ctx.User.GetPartyIdAsInt();
                 int authLevel = ctx.User.GetAuthenticationLevel();
 
-                request.Properties.Add("partyId", partyId.ToString());
-                request.Properties.Add("authLevel", authLevel.ToString());
+                request.Properties.Add("partyId", partyId?.ToString(CultureInfo.InvariantCulture) ?? "");
+                request.Properties.Add("authLevel", authLevel.ToString(CultureInfo.InvariantCulture));
 
                 if (userId != null)
                 {
-                    request.Properties.Add("userId", userId.ToString());
+                    request.Properties.Add("userId", userId?.ToString(CultureInfo.InvariantCulture) ?? "");
                 }
 
                 if (orgNumber != null)
                 {
-                    request.Properties.Add("orgNumber", orgNumber.ToString());
+                    request.Properties.Add("orgNumber", orgNumber?.ToString(CultureInfo.InvariantCulture) ?? "");
                 }
             }
         }
diff --git a/src/Altinn.App.Core/Configuration/AppSettings.cs b/src/Altinn.App.Core/Configuration/AppSettings.cs
index 59c70b419..962226e02 100644
--- a/src/Altinn.App.Core/Configuration/AppSettings.cs
+++ b/src/Altinn.App.Core/Configuration/AppSettings.cs
@@ -6,6 +6,7 @@ namespace Altinn.App.Core.Configuration;
 // TODO: IOptions validation so that we know which of these properties are required
 public class AppSettings
 {
+#pragma warning disable CA1707 // Identifiers should not contain underscores
     /// <summary>
     /// Constant for the location of json schema file
     /// </summary>
@@ -15,6 +16,7 @@ public class AppSettings
     /// Constant for the location of validation configuration file
     /// </summary>
     public const string VALIDATION_CONFIG_FILENAME = "validation.json";
+#pragma warning restore CA1707 // Identifiers should not contain underscores
 
     /// <summary>
     /// The app configuration baseUrl where files are stored in the container
diff --git a/src/Altinn.App.Core/Constants/AuthzConstants.cs b/src/Altinn.App.Core/Constants/AuthzConstants.cs
index 97517042d..bd11696f6 100644
--- a/src/Altinn.App.Core/Constants/AuthzConstants.cs
+++ b/src/Altinn.App.Core/Constants/AuthzConstants.cs
@@ -5,6 +5,7 @@ namespace Altinn.App.Core.Constants;
 /// </summary>
 public static class AuthzConstants
 {
+#pragma warning disable CA1707 // Identifiers should not contain underscores
     /// <summary>
     /// Policy tag for reading an instance.
     /// </summary>
@@ -24,4 +25,5 @@ public static class AuthzConstants
     /// Policy tag for authorizing client scope.
     /// </summary>
     public const string POLICY_INSTANCE_COMPLETE = "InstanceComplete";
+#pragma warning restore CA1707 // Identifiers should not contain underscores
 }
diff --git a/src/Altinn.App.Core/EFormidling/Implementation/DefaultEFormidlingService.cs b/src/Altinn.App.Core/EFormidling/Implementation/DefaultEFormidlingService.cs
index dbe3e2d61..b96fd3748 100644
--- a/src/Altinn.App.Core/EFormidling/Implementation/DefaultEFormidlingService.cs
+++ b/src/Altinn.App.Core/EFormidling/Implementation/DefaultEFormidlingService.cs
@@ -1,4 +1,5 @@
 using System.Diagnostics;
+using System.Globalization;
 using Altinn.App.Core.Configuration;
 using Altinn.App.Core.Constants;
 using Altinn.App.Core.EFormidling.Interface;
@@ -196,7 +197,7 @@ private async Task SendInstanceData(Instance instance, Dictionary<string, string
         ApplicationMetadata applicationMetadata = await _appMetadata.GetApplicationMetadata();
 
         Guid instanceGuid = Guid.Parse(instance.Id.Split("/")[1]);
-        int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId);
+        int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId, CultureInfo.InvariantCulture);
         foreach (DataElement dataElement in instance.Data)
         {
             if (!applicationMetadata.EFormidling.DataTypes.Contains(dataElement.DataType))
diff --git a/src/Altinn.App.Core/Extensions/ClaimsPrincipalExtensions.cs b/src/Altinn.App.Core/Extensions/ClaimsPrincipalExtensions.cs
index c1fd384cb..5c9eceee7 100644
--- a/src/Altinn.App.Core/Extensions/ClaimsPrincipalExtensions.cs
+++ b/src/Altinn.App.Core/Extensions/ClaimsPrincipalExtensions.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Security.Claims;
 using AltinnCore.Authentication.Constants;
 
@@ -16,13 +17,13 @@ public static class ClaimsPrincipalExtensions
         int? userId = GetUserIdAsInt(user);
         if (userId.HasValue)
         {
-            return userId.Value.ToString();
+            return userId.Value.ToString(CultureInfo.InvariantCulture);
         }
 
         int? orgId = GetOrgNumber(user);
         if (orgId.HasValue)
         {
-            return orgId.Value.ToString();
+            return orgId.Value.ToString(CultureInfo.InvariantCulture);
         }
 
         return null;
diff --git a/src/Altinn.App.Core/Features/Action/SigningUserAction.cs b/src/Altinn.App.Core/Features/Action/SigningUserAction.cs
index f574406f8..99a28f678 100644
--- a/src/Altinn.App.Core/Features/Action/SigningUserAction.cs
+++ b/src/Altinn.App.Core/Features/Action/SigningUserAction.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using Altinn.App.Core.Internal.App;
 using Altinn.App.Core.Internal.Process;
 using Altinn.App.Core.Internal.Process.Elements;
@@ -149,7 +150,7 @@ await _profileClient.GetUserProfile(userId)
 
         return new Signee
         {
-            UserId = userProfile.UserId.ToString(),
+            UserId = userProfile.UserId.ToString(CultureInfo.InvariantCulture),
             PersonNumber = userProfile.Party.SSN,
             OrganisationNumber = userProfile.Party.OrgNumber,
         };
diff --git a/src/Altinn.App.Core/Features/DataLists/DataListsFactory.cs b/src/Altinn.App.Core/Features/DataLists/DataListsFactory.cs
index 5e1a3cf6c..098857796 100644
--- a/src/Altinn.App.Core/Features/DataLists/DataListsFactory.cs
+++ b/src/Altinn.App.Core/Features/DataLists/DataListsFactory.cs
@@ -25,7 +25,7 @@ public IDataListProvider GetDataListProvider(string listId)
     {
         foreach (var dataListProvider in _dataListProviders)
         {
-            if (dataListProvider.Id.ToLower().Equals(listId.ToLower()))
+            if (dataListProvider.Id.Equals(listId, StringComparison.OrdinalIgnoreCase))
             {
                 return dataListProvider;
             }
diff --git a/src/Altinn.App.Core/Features/DataLists/InstanceDataListsFactory.cs b/src/Altinn.App.Core/Features/DataLists/InstanceDataListsFactory.cs
index eb24f5ded..04eb81ef0 100644
--- a/src/Altinn.App.Core/Features/DataLists/InstanceDataListsFactory.cs
+++ b/src/Altinn.App.Core/Features/DataLists/InstanceDataListsFactory.cs
@@ -25,7 +25,7 @@ public IInstanceDataListProvider GetDataListProvider(string listId)
     {
         foreach (var instanceDataListProvider in _instanceDataListProviders)
         {
-            if (instanceDataListProvider.Id.ToLower().Equals(listId.ToLower()))
+            if (instanceDataListProvider.Id.Equals(listId, StringComparison.OrdinalIgnoreCase))
             {
                 return instanceDataListProvider;
             }
diff --git a/src/Altinn.App.Core/Features/Options/Altinn2Provider/Altinn2MetadataApiClient.cs b/src/Altinn.App.Core/Features/Options/Altinn2Provider/Altinn2MetadataApiClient.cs
index d2973c618..ad8a64a13 100644
--- a/src/Altinn.App.Core/Features/Options/Altinn2Provider/Altinn2MetadataApiClient.cs
+++ b/src/Altinn.App.Core/Features/Options/Altinn2Provider/Altinn2MetadataApiClient.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using Altinn.App.Core.Helpers;
 
 namespace Altinn.App.Core.Features.Options.Altinn2Provider;
@@ -29,12 +30,12 @@ public Altinn2MetadataApiClient(HttpClient client)
     public async Task<MetadataCodelistResponse> GetAltinn2Codelist(string id, string langCode, int? version = null)
     {
         var response = await _client.GetAsync(
-            $"https://www.altinn.no/api/metadata/codelists/{id}/{version?.ToString() ?? string.Empty}?language={langCode}"
+            $"https://www.altinn.no/api/metadata/codelists/{id}/{version?.ToString(CultureInfo.InvariantCulture) ?? string.Empty}?language={langCode}"
         );
         if (response.StatusCode == System.Net.HttpStatusCode.NotFound)
         {
             response = await _client.GetAsync(
-                $"https://www.altinn.no/api/metadata/codelists/{id}/{version?.ToString() ?? string.Empty}"
+                $"https://www.altinn.no/api/metadata/codelists/{id}/{version?.ToString(CultureInfo.InvariantCulture) ?? string.Empty}"
             );
         }
         response.EnsureSuccessStatusCode();
diff --git a/src/Altinn.App.Core/Features/Validation/Helpers/ModelStateHelpers.cs b/src/Altinn.App.Core/Features/Validation/Helpers/ModelStateHelpers.cs
index a5ab2fc19..a22871460 100644
--- a/src/Altinn.App.Core/Features/Validation/Helpers/ModelStateHelpers.cs
+++ b/src/Altinn.App.Core/Features/Validation/Helpers/ModelStateHelpers.cs
@@ -66,7 +66,7 @@ private static (ValidationIssueSeverity Severity, string Message) GetSeverityFro
         GeneralSettings generalSettings
     )
     {
-        if (originalMessage.StartsWith(generalSettings.SoftValidationPrefix))
+        if (originalMessage.StartsWith(generalSettings.SoftValidationPrefix, StringComparison.Ordinal))
         {
             return (
                 ValidationIssueSeverity.Warning,
@@ -75,7 +75,7 @@ GeneralSettings generalSettings
         }
 
 #pragma warning disable CS0618 // Type or member is obsolete
-        if (originalMessage.StartsWith(generalSettings.FixedValidationPrefix))
+        if (originalMessage.StartsWith(generalSettings.FixedValidationPrefix, StringComparison.Ordinal))
         {
             return (
                 ValidationIssueSeverity.Fixed,
@@ -84,7 +84,7 @@ GeneralSettings generalSettings
         }
 #pragma warning restore CS0618 // Type or member is obsolete
 
-        if (originalMessage.StartsWith(generalSettings.InfoValidationPrefix))
+        if (originalMessage.StartsWith(generalSettings.InfoValidationPrefix, StringComparison.Ordinal))
         {
             return (
                 ValidationIssueSeverity.Informational,
@@ -92,7 +92,7 @@ GeneralSettings generalSettings
             );
         }
 
-        if (originalMessage.StartsWith(generalSettings.SuccessValidationPrefix))
+        if (originalMessage.StartsWith(generalSettings.SuccessValidationPrefix, StringComparison.Ordinal))
         {
             return (
                 ValidationIssueSeverity.Success,
diff --git a/src/Altinn.App.Core/Helpers/AppTextHelper.cs b/src/Altinn.App.Core/Helpers/AppTextHelper.cs
index d441fc2ee..9d0e62d4e 100644
--- a/src/Altinn.App.Core/Helpers/AppTextHelper.cs
+++ b/src/Altinn.App.Core/Helpers/AppTextHelper.cs
@@ -1,3 +1,5 @@
+using System.Globalization;
+
 namespace Altinn.App.Core.Helpers;
 
 /// <summary>
@@ -37,7 +39,7 @@ string languageId
                     stringList[i] = textParams[i];
                 }
 
-                text = string.Format(text, stringList);
+                text = string.Format(CultureInfo.InvariantCulture, text, stringList);
             }
         }
 
diff --git a/src/Altinn.App.Core/Helpers/AuthenticationHelper.cs b/src/Altinn.App.Core/Helpers/AuthenticationHelper.cs
index 8d7a7cc34..f8bd5a49f 100644
--- a/src/Altinn.App.Core/Helpers/AuthenticationHelper.cs
+++ b/src/Altinn.App.Core/Helpers/AuthenticationHelper.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Security.Claims;
 using AltinnCore.Authentication.Constants;
 using Microsoft.AspNetCore.Http;
@@ -22,9 +23,9 @@ public static int GetUserId(HttpContext context)
         {
             foreach (Claim claim in context.User.Claims)
             {
-                if (claim.Type.Equals(AltinnCoreClaimTypes.UserId))
+                if (claim.Type.Equals(AltinnCoreClaimTypes.UserId, StringComparison.Ordinal))
                 {
-                    userId = Convert.ToInt32(claim.Value);
+                    userId = Convert.ToInt32(claim.Value, CultureInfo.InvariantCulture);
                 }
             }
         }
diff --git a/src/Altinn.App.Core/Helpers/DataModel/DataModel.cs b/src/Altinn.App.Core/Helpers/DataModel/DataModel.cs
index ae7b5a0d6..361d9098a 100644
--- a/src/Altinn.App.Core/Helpers/DataModel/DataModel.cs
+++ b/src/Altinn.App.Core/Helpers/DataModel/DataModel.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Reflection;
 using System.Text.RegularExpressions;
 
@@ -224,7 +225,7 @@ internal static (string key, int? index) ParseKeyPart(string keypart)
             return (keypart, null);
         }
         var match = _keyPartRegex.Match(keypart);
-        return (match.Groups[1].Value, int.Parse(match.Groups[2].Value));
+        return (match.Groups[1].Value, int.Parse(match.Groups[2].Value, CultureInfo.InvariantCulture));
     }
 
     private static void AddIndiciesRecursive(
diff --git a/src/Altinn.App.Core/Helpers/InstantiationHelper.cs b/src/Altinn.App.Core/Helpers/InstantiationHelper.cs
index f0b31da71..122e9dac6 100644
--- a/src/Altinn.App.Core/Helpers/InstantiationHelper.cs
+++ b/src/Altinn.App.Core/Helpers/InstantiationHelper.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using Altinn.Platform.Register.Enums;
 using Altinn.Platform.Register.Models;
 using Altinn.Platform.Storage.Interface.Models;
@@ -110,9 +111,12 @@ public static bool IsPartyAllowedToInstantiate(Party? party, PartyTypesAllowed?
 
         bool isSubUnit =
             party.UnitType != null
-            && (SUB_UNIT_CODE.Equals(party.UnitType.Trim()) || SUB_UNIT_CODE_AAFY.Equals(party.UnitType.Trim()));
+            && (
+                SUB_UNIT_CODE.Equals(party.UnitType.Trim(), StringComparison.Ordinal)
+                || SUB_UNIT_CODE_AAFY.Equals(party.UnitType.Trim(), StringComparison.Ordinal)
+            );
         bool isMainUnit = !isSubUnit;
-        bool isKbo = party.UnitType != null && BANKRUPTCY_CODE.Equals(party.UnitType.Trim());
+        bool isKbo = party.UnitType != null && BANKRUPTCY_CODE.Equals(party.UnitType.Trim(), StringComparison.Ordinal);
 
         switch (partyType)
         {
@@ -192,19 +196,23 @@ public static InstanceOwner PartyToInstanceOwner(Party party)
     {
         if (!string.IsNullOrEmpty(party.SSN))
         {
-            return new() { PartyId = party.PartyId.ToString(), PersonNumber = party.SSN, };
+            return new() { PartyId = party.PartyId.ToString(CultureInfo.InvariantCulture), PersonNumber = party.SSN, };
         }
         else if (!string.IsNullOrEmpty(party.OrgNumber))
         {
-            return new() { PartyId = party.PartyId.ToString(), OrganisationNumber = party.OrgNumber, };
+            return new()
+            {
+                PartyId = party.PartyId.ToString(CultureInfo.InvariantCulture),
+                OrganisationNumber = party.OrgNumber,
+            };
         }
         else if (party.PartyTypeName.Equals(PartyType.SelfIdentified))
         {
-            return new() { PartyId = party.PartyId.ToString(), Username = party.Name, };
+            return new() { PartyId = party.PartyId.ToString(CultureInfo.InvariantCulture), Username = party.Name, };
         }
         return new()
         {
-            PartyId = party.PartyId.ToString(),
+            PartyId = party.PartyId.ToString(CultureInfo.InvariantCulture),
             // instanceOwnerPartyType == "unknown"
         };
     }
diff --git a/src/Altinn.App.Core/Helpers/JsonSerializerIgnorePrefix.cs b/src/Altinn.App.Core/Helpers/JsonSerializerIgnorePrefix.cs
index 79a3c0ec9..81edde649 100644
--- a/src/Altinn.App.Core/Helpers/JsonSerializerIgnorePrefix.cs
+++ b/src/Altinn.App.Core/Helpers/JsonSerializerIgnorePrefix.cs
@@ -22,7 +22,7 @@ internal static JsonSerializerOptions GetOptions(string prefix)
                 if (ti.Kind != JsonTypeInfoKind.Object)
                     return;
 
-                ti.Properties.RemoveAll(prop => prop.Name.StartsWith(prefix));
+                ti.Properties.RemoveAll(prop => prop.Name.StartsWith(prefix, StringComparison.Ordinal));
             };
 
             JsonSerializerOptions newOptions =
diff --git a/src/Altinn.App.Core/Helpers/MultiDecisionHelper.cs b/src/Altinn.App.Core/Helpers/MultiDecisionHelper.cs
index 7b6afbe31..1cf269924 100644
--- a/src/Altinn.App.Core/Helpers/MultiDecisionHelper.cs
+++ b/src/Altinn.App.Core/Helpers/MultiDecisionHelper.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Security.Claims;
 using Altinn.App.Core.Models;
 using Altinn.Authorization.ABAC.Xacml.JsonProfile;
@@ -94,7 +95,7 @@ private static List<XacmlJsonCategory> CreateMultipleActionCategory(List<string>
         {
             XacmlJsonCategory actionCategory;
             actionCategory = DecisionHelper.CreateActionCategory(actionType, true);
-            actionCategory.Id = ActionId + counter.ToString();
+            actionCategory.Id = ActionId + counter.ToString(CultureInfo.InvariantCulture);
             actionCategories.Add(actionCategory);
             counter++;
         }
diff --git a/src/Altinn.App.Core/Helpers/ObjectUtils.cs b/src/Altinn.App.Core/Helpers/ObjectUtils.cs
index ba40cada1..8ac0a1a84 100644
--- a/src/Altinn.App.Core/Helpers/ObjectUtils.cs
+++ b/src/Altinn.App.Core/Helpers/ObjectUtils.cs
@@ -25,7 +25,7 @@ public static void InitializeAltinnRowId(object model, int depth = 64)
             );
         }
 
-        if (type.Namespace?.StartsWith("System") == true)
+        if (type.Namespace?.StartsWith("System", StringComparison.Ordinal) == true)
         {
             return; // System.DateTime.Now causes infinite recursion, and we shuldn't recurse into system types anyway.
         }
@@ -90,7 +90,7 @@ public static void PrepareModelForXmlStorage(object model, int depth = 64)
             );
         }
 
-        if (type.Namespace?.StartsWith("System") == true)
+        if (type.Namespace?.StartsWith("System", StringComparison.Ordinal) == true)
         {
             return;
         }
@@ -190,7 +190,7 @@ public static void RemoveAltinnRowId(object model, int depth = 64)
             );
         }
         var type = model.GetType();
-        if (type.Namespace?.StartsWith("System") == true)
+        if (type.Namespace?.StartsWith("System", StringComparison.Ordinal) == true)
         {
             return; // System.DateTime.Now causes infinite recursion, and we shuldn't recurse into system types anyway.
         }
diff --git a/src/Altinn.App.Core/Helpers/PathHelper.cs b/src/Altinn.App.Core/Helpers/PathHelper.cs
index c3fb2d24e..a75a8bdfc 100644
--- a/src/Altinn.App.Core/Helpers/PathHelper.cs
+++ b/src/Altinn.App.Core/Helpers/PathHelper.cs
@@ -16,7 +16,7 @@ public static bool ValidateLegalFilePath(string legalPath, string filePath)
         var fullRootedFolder = Path.GetFullPath(legalPath + Path.DirectorySeparatorChar);
         var expandedFilename = Path.GetFullPath(filePath);
 
-        return expandedFilename.StartsWith(fullRootedFolder);
+        return expandedFilename.StartsWith(fullRootedFolder, StringComparison.Ordinal);
     }
 
     /// <summary>
diff --git a/src/Altinn.App.Core/Helpers/SelfLinkHelper.cs b/src/Altinn.App.Core/Helpers/SelfLinkHelper.cs
index d7ee798ae..b52ca7176 100644
--- a/src/Altinn.App.Core/Helpers/SelfLinkHelper.cs
+++ b/src/Altinn.App.Core/Helpers/SelfLinkHelper.cs
@@ -21,7 +21,7 @@ public static void SetInstanceAppSelfLinks(Instance instance, HttpRequest reques
 
         string selfLink = $"{host}{url}";
 
-        int start = selfLink.IndexOf("/instances");
+        int start = selfLink.IndexOf("/instances", StringComparison.OrdinalIgnoreCase);
         if (start > 0)
         {
             selfLink = string.Concat(selfLink.AsSpan(0, start), "/instances");
@@ -29,7 +29,7 @@ public static void SetInstanceAppSelfLinks(Instance instance, HttpRequest reques
 
         selfLink += $"/{instance.Id}";
 
-        if (!selfLink.EndsWith(instance.Id))
+        if (!selfLink.EndsWith(instance.Id, StringComparison.OrdinalIgnoreCase))
         {
             selfLink += instance.Id;
         }
@@ -66,7 +66,7 @@ HttpRequest request
 
         string selfLink = $"{host}{url}";
 
-        int start = selfLink.IndexOf("/instances");
+        int start = selfLink.IndexOf("/instances", StringComparison.OrdinalIgnoreCase);
         if (start > 0)
         {
             selfLink = string.Concat(selfLink.AsSpan(0, start), "/instances");
diff --git a/src/Altinn.App.Core/Helpers/ShadowFieldsConverter.cs b/src/Altinn.App.Core/Helpers/ShadowFieldsConverter.cs
index 3bf92e0f7..86325ddb1 100644
--- a/src/Altinn.App.Core/Helpers/ShadowFieldsConverter.cs
+++ b/src/Altinn.App.Core/Helpers/ShadowFieldsConverter.cs
@@ -23,7 +23,7 @@ public void ModifyPrefixInfo(JsonTypeInfo ti)
         if (ti.Kind != JsonTypeInfoKind.Object)
             return;
 
-        ti.Properties.RemoveAll(prop => prop.Name.StartsWith(_ignorePrefix));
+        ti.Properties.RemoveAll(prop => prop.Name.StartsWith(_ignorePrefix, StringComparison.Ordinal));
     }
 }
 
diff --git a/src/Altinn.App.Core/Helpers/UserHelper.cs b/src/Altinn.App.Core/Helpers/UserHelper.cs
index ecaa9c703..c1eeb45bd 100644
--- a/src/Altinn.App.Core/Helpers/UserHelper.cs
+++ b/src/Altinn.App.Core/Helpers/UserHelper.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Security.Claims;
 using Altinn.App.Core.Configuration;
 using Altinn.App.Core.Internal.Profile;
@@ -47,24 +48,24 @@ public async Task<UserContext> GetUserContext(HttpContext context)
 
         foreach (Claim claim in context.User.Claims)
         {
-            if (claim.Type.Equals(AltinnCoreClaimTypes.UserName))
+            if (claim.Type.Equals(AltinnCoreClaimTypes.UserName, StringComparison.Ordinal))
             {
                 userContext.UserName = claim.Value;
             }
 
-            if (claim.Type.Equals(AltinnCoreClaimTypes.UserId))
+            if (claim.Type.Equals(AltinnCoreClaimTypes.UserId, StringComparison.Ordinal))
             {
-                userContext.UserId = Convert.ToInt32(claim.Value);
+                userContext.UserId = Convert.ToInt32(claim.Value, CultureInfo.InvariantCulture);
             }
 
-            if (claim.Type.Equals(AltinnCoreClaimTypes.PartyID))
+            if (claim.Type.Equals(AltinnCoreClaimTypes.PartyID, StringComparison.Ordinal))
             {
-                userContext.PartyId = Convert.ToInt32(claim.Value);
+                userContext.PartyId = Convert.ToInt32(claim.Value, CultureInfo.InvariantCulture);
             }
 
-            if (claim.Type.Equals(AltinnCoreClaimTypes.AuthenticationLevel))
+            if (claim.Type.Equals(AltinnCoreClaimTypes.AuthenticationLevel, StringComparison.Ordinal))
             {
-                userContext.AuthenticationLevel = Convert.ToInt32(claim.Value);
+                userContext.AuthenticationLevel = Convert.ToInt32(claim.Value, CultureInfo.InvariantCulture);
             }
         }
 
@@ -75,7 +76,10 @@ await _profileClient.GetUserProfile(userContext.UserId)
 
         if (context.Request.Cookies[_settings.GetAltinnPartyCookieName] != null)
         {
-            userContext.PartyId = Convert.ToInt32(context.Request.Cookies[_settings.GetAltinnPartyCookieName]);
+            userContext.PartyId = Convert.ToInt32(
+                context.Request.Cookies[_settings.GetAltinnPartyCookieName],
+                CultureInfo.InvariantCulture
+            );
         }
 
         if (userContext.PartyId == userProfile.PartyId)
diff --git a/src/Altinn.App.Core/Implementation/AppResourcesSI.cs b/src/Altinn.App.Core/Implementation/AppResourcesSI.cs
index 6a0e00a8d..5adb31c4f 100644
--- a/src/Altinn.App.Core/Implementation/AppResourcesSI.cs
+++ b/src/Altinn.App.Core/Implementation/AppResourcesSI.cs
@@ -212,7 +212,7 @@ public string GetClassRefForLogicDataType(string dataType)
         Application application = GetApplication();
         string classRef = string.Empty;
 
-        DataType? element = application.DataTypes.SingleOrDefault(d => d.Id.Equals(dataType));
+        DataType? element = application.DataTypes.SingleOrDefault(d => d.Id.Equals(dataType, StringComparison.Ordinal));
 
         if (element != null)
         {
diff --git a/src/Altinn.App.Core/Implementation/DefaultAppEvents.cs b/src/Altinn.App.Core/Implementation/DefaultAppEvents.cs
index 729ac6784..19a697a17 100644
--- a/src/Altinn.App.Core/Implementation/DefaultAppEvents.cs
+++ b/src/Altinn.App.Core/Implementation/DefaultAppEvents.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using Altinn.App.Core.Internal.App;
 using Altinn.App.Core.Internal.Data;
 using Altinn.App.Core.Internal.Instances;
@@ -69,7 +70,7 @@ private async Task AutoDeleteDataElements(Instance instance)
                 _dataClient.DeleteData(
                     applicationMetadata.Org,
                     applicationMetadata.AppIdentifier.App,
-                    int.Parse(instance.InstanceOwner.PartyId),
+                    int.Parse(instance.InstanceOwner.PartyId, CultureInfo.InvariantCulture),
                     Guid.Parse(item.InstanceGuid),
                     Guid.Parse(item.Id),
                     true
diff --git a/src/Altinn.App.Core/Implementation/PrefillSI.cs b/src/Altinn.App.Core/Implementation/PrefillSI.cs
index 0a839cca1..895380dc8 100644
--- a/src/Altinn.App.Core/Implementation/PrefillSI.cs
+++ b/src/Altinn.App.Core/Implementation/PrefillSI.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Reflection;
 using Altinn.App.Core.Features;
 using Altinn.App.Core.Helpers;
@@ -93,7 +94,7 @@ public async Task PrefillDataModel(
             _allowOverwrite = allowOverwriteToken.ToObject<bool>();
         }
 
-        Party? party = await _altinnPartyClientClient.GetParty(int.Parse(partyId));
+        Party? party = await _altinnPartyClientClient.GetParty(int.Parse(partyId, CultureInfo.InvariantCulture));
         if (party == null)
         {
             string errorMessage = $"Could find party for partyId: {partyId}";
diff --git a/src/Altinn.App.Core/Infrastructure/Clients/KeyVault/SecretsLocalClient.cs b/src/Altinn.App.Core/Infrastructure/Clients/KeyVault/SecretsLocalClient.cs
index 042851d88..ff254da36 100644
--- a/src/Altinn.App.Core/Infrastructure/Clients/KeyVault/SecretsLocalClient.cs
+++ b/src/Altinn.App.Core/Infrastructure/Clients/KeyVault/SecretsLocalClient.cs
@@ -46,9 +46,9 @@ public KeyVaultClient GetKeyVaultClient()
     }
 
     /// <inheritdoc />
-    public async Task<string> GetSecretAsync(string secretId)
+    public async Task<string> GetSecretAsync(string secretName)
     {
-        string token = GetTokenFromSecrets(secretId);
+        string token = GetTokenFromSecrets(secretName);
         return await Task.FromResult(token);
     }
 
diff --git a/src/Altinn.App.Core/Infrastructure/Clients/Profile/ProfileClientCachingDecorator.cs b/src/Altinn.App.Core/Infrastructure/Clients/Profile/ProfileClientCachingDecorator.cs
index d0a1e4133..cab458bdb 100644
--- a/src/Altinn.App.Core/Infrastructure/Clients/Profile/ProfileClientCachingDecorator.cs
+++ b/src/Altinn.App.Core/Infrastructure/Clients/Profile/ProfileClientCachingDecorator.cs
@@ -22,7 +22,7 @@ public class ProfileClientCachingDecorator : IProfileClient
     public ProfileClientCachingDecorator(
         IProfileClient decoratedService,
         IMemoryCache memoryCache,
-        IOptions<CacheSettings> _settings
+        IOptions<CacheSettings> settings
     )
     {
         _decoratedService = decoratedService;
@@ -30,7 +30,7 @@ IOptions<CacheSettings> _settings
 
         _cacheOptions = new()
         {
-            AbsoluteExpirationRelativeToNow = TimeSpan.FromSeconds(_settings.Value.ProfileCacheLifetimeSeconds)
+            AbsoluteExpirationRelativeToNow = TimeSpan.FromSeconds(settings.Value.ProfileCacheLifetimeSeconds)
         };
     }
 
diff --git a/src/Altinn.App.Core/Infrastructure/Clients/Storage/InstanceClient.cs b/src/Altinn.App.Core/Infrastructure/Clients/Storage/InstanceClient.cs
index c6cecad87..609f618ae 100644
--- a/src/Altinn.App.Core/Infrastructure/Clients/Storage/InstanceClient.cs
+++ b/src/Altinn.App.Core/Infrastructure/Clients/Storage/InstanceClient.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Net;
 using System.Net.Http.Headers;
 using System.Text;
@@ -60,10 +61,10 @@ public InstanceClient(
     }
 
     /// <inheritdoc />
-    public async Task<Instance> GetInstance(string app, string org, int instanceOwnerPartyId, Guid instanceGuid)
+    public async Task<Instance> GetInstance(string app, string org, int instanceOwnerPartyId, Guid instanceId)
     {
-        using var activity = _telemetry?.StartGetInstanceByGuidActivity(instanceGuid);
-        string instanceIdentifier = $"{instanceOwnerPartyId}/{instanceGuid}";
+        using var activity = _telemetry?.StartGetInstanceByGuidActivity(instanceId);
+        string instanceIdentifier = $"{instanceOwnerPartyId}/{instanceId}";
 
         string apiUrl = $"instances/{instanceIdentifier}";
         string token = JwtTokenUtil.GetTokenFromContext(_httpContextAccessor.HttpContext, _settings.RuntimeCookieName);
@@ -78,7 +79,7 @@ public async Task<Instance> GetInstance(string app, string org, int instanceOwne
         }
         else
         {
-            _logger.LogError($"Unable to fetch instance with instance id {instanceGuid}");
+            _logger.LogError($"Unable to fetch instance with instance id {instanceId}");
             throw await PlatformHttpException.CreateAsync(response);
         }
     }
@@ -90,7 +91,7 @@ public async Task<Instance> GetInstance(Instance instance)
         using var activity = _telemetry?.StartGetInstanceByInstanceActivity(instanceGuid);
         string app = instance.AppId.Split("/")[1];
         string org = instance.Org;
-        int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId);
+        int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId, CultureInfo.InvariantCulture);
 
         return await GetInstance(app, org, instanceOwnerPartyId, instanceGuid);
     }
diff --git a/src/Altinn.App.Core/Infrastructure/Clients/Storage/InstanceEventClient.cs b/src/Altinn.App.Core/Infrastructure/Clients/Storage/InstanceEventClient.cs
index 97db5f58e..5224647c4 100644
--- a/src/Altinn.App.Core/Infrastructure/Clients/Storage/InstanceEventClient.cs
+++ b/src/Altinn.App.Core/Infrastructure/Clients/Storage/InstanceEventClient.cs
@@ -1,4 +1,5 @@
 using System.Diagnostics;
+using System.Globalization;
 using System.Net.Http.Headers;
 using System.Text;
 using Altinn.App.Core.Configuration;
@@ -66,7 +67,7 @@ string to
             StringBuilder bld = new StringBuilder();
             foreach (string type in eventTypes)
             {
-                bld.Append($"{paramSeparator}eventTypes={type}");
+                bld.Append(CultureInfo.InvariantCulture, $"{paramSeparator}eventTypes={type}");
                 paramSeparator = '&';
             }
 
diff --git a/src/Altinn.App.Core/Infrastructure/Clients/Storage/TextClient.cs b/src/Altinn.App.Core/Infrastructure/Clients/Storage/TextClient.cs
index f037eec7e..d35eba899 100644
--- a/src/Altinn.App.Core/Infrastructure/Clients/Storage/TextClient.cs
+++ b/src/Altinn.App.Core/Infrastructure/Clients/Storage/TextClient.cs
@@ -62,7 +62,7 @@ IMemoryCache memoryCache
     public async Task<TextResource?> GetText(string org, string app, string language)
     {
         TextResource? textResource = null;
-        string cacheKey = $"{org}-{app}-{language.ToLower()}";
+        string cacheKey = $"{org}-{app}-{language.ToLowerInvariant()}";
 
         if (!_memoryCache.TryGetValue(cacheKey, out textResource))
         {
diff --git a/src/Altinn.App.Core/Internal/Data/DataService.cs b/src/Altinn.App.Core/Internal/Data/DataService.cs
index 8f9e822fd..bbe27960a 100644
--- a/src/Altinn.App.Core/Internal/Data/DataService.cs
+++ b/src/Altinn.App.Core/Internal/Data/DataService.cs
@@ -27,7 +27,9 @@ public DataService(IDataClient dataClient, IAppMetadata appMetadata)
     /// <inheritdoc/>
     public async Task<(Guid dataElementId, T? model)> GetByType<T>(Instance instance, string dataTypeId)
     {
-        DataElement? dataElement = instance.Data.SingleOrDefault(d => d.DataType.Equals(dataTypeId));
+        DataElement? dataElement = instance.Data.SingleOrDefault(d =>
+            d.DataType.Equals(dataTypeId, StringComparison.Ordinal)
+        );
 
         if (dataElement == null)
         {
diff --git a/src/Altinn.App.Core/Internal/Expressions/ExpressionEvaluator.cs b/src/Altinn.App.Core/Internal/Expressions/ExpressionEvaluator.cs
index 30ffbf3eb..45b607576 100644
--- a/src/Altinn.App.Core/Internal/Expressions/ExpressionEvaluator.cs
+++ b/src/Altinn.App.Core/Internal/Expressions/ExpressionEvaluator.cs
@@ -266,7 +266,7 @@ private static string Round(object?[] args)
         int precision = 0;
         if (args.Length == 2 && args[1] is not null)
         {
-            precision = Convert.ToInt32(args[1]);
+            precision = Convert.ToInt32(args[1], CultureInfo.InvariantCulture);
         }
 
         return number.Value.ToString($"N{precision}", CultureInfo.InvariantCulture);
@@ -386,7 +386,7 @@ bool ab
                     $"Expected number, got value {(ab ? "true" : "false")}"
                 ),
             string s => ParseNumber(s),
-            IConvertible c => Convert.ToDouble(c),
+            IConvertible c => Convert.ToDouble(c, CultureInfo.InvariantCulture),
             _ => null
         };
     }
@@ -398,7 +398,7 @@ bool ab
             return PrepareBooleanArg(args[0]) ? args[1] : null;
         }
 
-        if (args.Length > 2 && !"else".Equals(args[2] as string, StringComparison.InvariantCultureIgnoreCase))
+        if (args.Length > 2 && !"else".Equals(args[2] as string, StringComparison.OrdinalIgnoreCase))
         {
             throw new ExpressionEvaluatorTypeErrorException("Expected third argument to be \"else\"");
         }
@@ -488,15 +488,15 @@ bool ab
         if (value is string svalue)
         {
             // Special case for "TruE" to be equal to true
-            if ("true".Equals(svalue, StringComparison.InvariantCultureIgnoreCase))
+            if ("true".Equals(svalue, StringComparison.OrdinalIgnoreCase))
             {
                 return "true";
             }
-            else if ("false".Equals(svalue, StringComparison.InvariantCultureIgnoreCase))
+            else if ("false".Equals(svalue, StringComparison.OrdinalIgnoreCase))
             {
                 return "false";
             }
-            else if ("null".Equals(svalue, StringComparison.InvariantCultureIgnoreCase))
+            else if ("null".Equals(svalue, StringComparison.OrdinalIgnoreCase))
             {
                 return null;
             }
@@ -523,7 +523,7 @@ bool ab
             throw new ExpressionEvaluatorTypeErrorException($"Expected 2 argument(s), got {args.Length}");
         }
 
-        return string.Equals(ToStringForEquals(args[0]), ToStringForEquals(args[1]), StringComparison.InvariantCulture);
+        return string.Equals(ToStringForEquals(args[0]), ToStringForEquals(args[1]), StringComparison.Ordinal);
     }
 
     private static object Argv(object?[] args, object[]? positionalArguments)
diff --git a/src/Altinn.App.Core/Internal/Pdf/PdfService.cs b/src/Altinn.App.Core/Internal/Pdf/PdfService.cs
index 7df8db7ba..600b21db3 100644
--- a/src/Altinn.App.Core/Internal/Pdf/PdfService.cs
+++ b/src/Altinn.App.Core/Internal/Pdf/PdfService.cs
@@ -195,8 +195,12 @@ private static string GetFileName(Instance instance, TextResource? textResource)
         }
 
         TextResourceElement? titleText =
-            textResource.Resources.Find(textResourceElement => textResourceElement.Id.Equals("appName"))
-            ?? textResource.Resources.Find(textResourceElement => textResourceElement.Id.Equals("ServiceName"));
+            textResource.Resources.Find(textResourceElement =>
+                textResourceElement.Id.Equals("appName", StringComparison.Ordinal)
+            )
+            ?? textResource.Resources.Find(textResourceElement =>
+                textResourceElement.Id.Equals("ServiceName", StringComparison.Ordinal)
+            );
 
         if (titleText != null && !string.IsNullOrEmpty(titleText.Value))
         {
diff --git a/src/Altinn.App.Core/Internal/Process/EventHandlers/EndEventEventHandler.cs b/src/Altinn.App.Core/Internal/Process/EventHandlers/EndEventEventHandler.cs
index 2e9dbe69c..9ebd24525 100644
--- a/src/Altinn.App.Core/Internal/Process/EventHandlers/EndEventEventHandler.cs
+++ b/src/Altinn.App.Core/Internal/Process/EventHandlers/EndEventEventHandler.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using Altinn.App.Core.Internal.App;
 using Altinn.App.Core.Internal.Instances;
 using Altinn.App.Core.Models;
@@ -48,7 +49,7 @@ private async Task AutoDeleteOnProcessEndIfEnabled(Instance instance)
         ApplicationMetadata applicationMetadata = await _appMetadata.GetApplicationMetadata();
         if (applicationMetadata.AutoDeleteOnProcessEnd && instance.Process?.Ended != null)
         {
-            int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId);
+            int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId, CultureInfo.InvariantCulture);
             await _instanceClient.DeleteInstance(instanceOwnerPartyId, instanceIdentifier.InstanceGuid, true);
         }
     }
diff --git a/src/Altinn.App.Core/Internal/Process/ExclusiveGatewayFactory.cs b/src/Altinn.App.Core/Internal/Process/ExclusiveGatewayFactory.cs
index 099be5bf6..6f3b69fd3 100644
--- a/src/Altinn.App.Core/Internal/Process/ExclusiveGatewayFactory.cs
+++ b/src/Altinn.App.Core/Internal/Process/ExclusiveGatewayFactory.cs
@@ -30,7 +30,7 @@ public ExclusiveGatewayFactory(IEnumerable<IProcessExclusiveGateway> gateways)
     public IProcessExclusiveGateway? GetProcessExclusiveGateway(string gatewayId)
     {
         return _gateways.FirstOrDefault(gateway =>
-            String.Equals(gateway.GatewayId, gatewayId, StringComparison.CurrentCultureIgnoreCase)
+            string.Equals(gateway.GatewayId, gatewayId, StringComparison.OrdinalIgnoreCase)
         );
     }
 }
diff --git a/src/Altinn.App.Core/Internal/Process/ExpressionsExclusiveGateway.cs b/src/Altinn.App.Core/Internal/Process/ExpressionsExclusiveGateway.cs
index a22f885dd..35bfe198d 100644
--- a/src/Altinn.App.Core/Internal/Process/ExpressionsExclusiveGateway.cs
+++ b/src/Altinn.App.Core/Internal/Process/ExpressionsExclusiveGateway.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Text;
 using System.Text.Json;
 using Altinn.App.Core.Features;
@@ -98,7 +99,7 @@ private async Task<LayoutEvaluatorState> GetLayoutEvaluatorState(
                     dataElementType,
                     instance.Org,
                     instance.AppId.Split("/")[1],
-                    int.Parse(instance.InstanceOwner.PartyId),
+                    int.Parse(instance.InstanceOwner.PartyId, CultureInfo.InvariantCulture),
                     dataGuid.Value
                 );
             }
diff --git a/src/Altinn.App.Core/Internal/Process/ProcessReader.cs b/src/Altinn.App.Core/Internal/Process/ProcessReader.cs
index f5f2aba41..c854cda60 100644
--- a/src/Altinn.App.Core/Internal/Process/ProcessReader.cs
+++ b/src/Altinn.App.Core/Internal/Process/ProcessReader.cs
@@ -24,7 +24,12 @@ public class ProcessReader : IProcessReader
     public ProcessReader(IProcessClient processClient, Telemetry? telemetry = null)
     {
         XmlSerializer serializer = new XmlSerializer(typeof(Definitions));
-        Definitions? definitions = (Definitions?)serializer.Deserialize(processClient.GetProcessDefinition());
+        // TODO: IO should be async
+        using var stream = processClient.GetProcessDefinition();
+#pragma warning disable CA5369 // Use XmlReader for 'XmlSerializer.Deserialize()'
+        // NOTE: this is trusted XML input, as it comes from the apps own code
+        Definitions? definitions = (Definitions?)serializer.Deserialize(stream);
+#pragma warning restore CA5369 // Use XmlReader for 'XmlSerializer.Deserialize()'
 
         _definitions =
             definitions
diff --git a/src/Altinn.App.Core/Internal/Process/ProcessTasks/Common/ProcessTaskFinalizer.cs b/src/Altinn.App.Core/Internal/Process/ProcessTasks/Common/ProcessTaskFinalizer.cs
index 996baeba0..5914c07ea 100644
--- a/src/Altinn.App.Core/Internal/Process/ProcessTasks/Common/ProcessTaskFinalizer.cs
+++ b/src/Altinn.App.Core/Internal/Process/ProcessTasks/Common/ProcessTaskFinalizer.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Text.Json;
 using Altinn.App.Core.Configuration;
 using Altinn.App.Core.Helpers;
@@ -85,7 +86,7 @@ DataType dataType
         Guid instanceGuid = Guid.Parse(instance.Id.Split("/")[1]);
         Guid dataGuid = Guid.Parse(dataElement.Id);
         string app = instance.AppId.Split("/")[1];
-        int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId);
+        int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId, CultureInfo.InvariantCulture);
         object data = await _dataClient.GetFormData(
             instanceGuid,
             modelType,
diff --git a/src/Altinn.App.Core/Internal/Process/ProcessTasks/Common/ProcessTaskInitializer.cs b/src/Altinn.App.Core/Internal/Process/ProcessTasks/Common/ProcessTaskInitializer.cs
index cd2850f72..3c96de722 100644
--- a/src/Altinn.App.Core/Internal/Process/ProcessTasks/Common/ProcessTaskInitializer.cs
+++ b/src/Altinn.App.Core/Internal/Process/ProcessTasks/Common/ProcessTaskInitializer.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using Altinn.App.Core.Features;
 using Altinn.App.Core.Helpers;
 using Altinn.App.Core.Internal.App;
@@ -107,7 +108,7 @@ private async Task UpdatePresentationTextsOnInstance(Instance instance, string d
         if (updatedValues.Count > 0)
         {
             Instance updatedInstance = await _instanceClient.UpdatePresentationTexts(
-                int.Parse(instance.Id.Split("/")[0]),
+                int.Parse(instance.Id.Split("/")[0], CultureInfo.InvariantCulture),
                 Guid.Parse(instance.Id.Split("/")[1]),
                 new PresentationTexts { Texts = updatedValues }
             );
@@ -129,7 +130,7 @@ private async Task UpdateDataValuesOnInstance(Instance instance, string dataType
         if (updatedValues.Count > 0)
         {
             Instance updatedInstance = await _instanceClient.UpdateDataValues(
-                int.Parse(instance.Id.Split("/")[0]),
+                int.Parse(instance.Id.Split("/")[0], CultureInfo.InvariantCulture),
                 Guid.Parse(instance.Id.Split("/")[1]),
                 new DataValues { Values = updatedValues }
             );
diff --git a/src/Altinn.App.Core/Internal/Validation/ValidationService.cs b/src/Altinn.App.Core/Internal/Validation/ValidationService.cs
index 46e2fcd4c..8b8916e12 100644
--- a/src/Altinn.App.Core/Internal/Validation/ValidationService.cs
+++ b/src/Altinn.App.Core/Internal/Validation/ValidationService.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using Altinn.App.Core.Features;
 using Altinn.App.Core.Internal.App;
 using Altinn.App.Core.Internal.AppModel;
@@ -139,7 +140,7 @@ public async Task<List<ValidationIssue>> ValidateDataElement(
 
             Guid instanceGuid = Guid.Parse(instance.Id.Split("/")[1]);
             string app = instance.AppId.Split("/")[1];
-            int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId);
+            int instanceOwnerPartyId = int.Parse(instance.InstanceOwner.PartyId, CultureInfo.InvariantCulture);
             var data = await _dataClient.GetFormData(
                 instanceGuid,
                 modelType,
diff --git a/src/Altinn.App.Core/Models/AppIdentifier.cs b/src/Altinn.App.Core/Models/AppIdentifier.cs
index 0b61d1988..3d1627612 100644
--- a/src/Altinn.App.Core/Models/AppIdentifier.cs
+++ b/src/Altinn.App.Core/Models/AppIdentifier.cs
@@ -93,8 +93,8 @@ public bool Equals(AppIdentifier? other)
     {
         return Org != null
             && App != null
-            && Org.Equals(other?.Org, StringComparison.CurrentCultureIgnoreCase)
-            && App.Equals(other?.App, StringComparison.CurrentCultureIgnoreCase);
+            && Org.Equals(other?.Org, StringComparison.OrdinalIgnoreCase)
+            && App.Equals(other?.App, StringComparison.OrdinalIgnoreCase);
     }
 
     ///<inheritDoc/>
diff --git a/src/Altinn.App.Core/Models/DataList.cs b/src/Altinn.App.Core/Models/DataList.cs
index 7bf0060ad..e9682b700 100644
--- a/src/Altinn.App.Core/Models/DataList.cs
+++ b/src/Altinn.App.Core/Models/DataList.cs
@@ -14,6 +14,8 @@ public class DataList
     /// Gets or sets the metadata of the DataList.
     /// </summary>
 #pragma warning disable IDE1006 // Naming Styles - public members should be PascalCase
+#pragma warning disable CA1707 // Identifiers should not contain underscores
     public DataListMetadata _metaData { get; set; } = new DataListMetadata();
+#pragma warning restore CA1707 // Identifiers should not contain underscores
 #pragma warning restore IDE1006 // Naming Styles
 }
diff --git a/src/Altinn.App.Core/Models/InstanceIdentifier.cs b/src/Altinn.App.Core/Models/InstanceIdentifier.cs
index 6363edd29..ae6ac5c94 100644
--- a/src/Altinn.App.Core/Models/InstanceIdentifier.cs
+++ b/src/Altinn.App.Core/Models/InstanceIdentifier.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using Altinn.Platform.Storage.Interface.Models;
 
 namespace Altinn.App.Core.Models;
@@ -110,7 +111,7 @@ public override string ToString()
     private static (int InstanceOwnerPartyId, Guid InstanceGuid) DeconstructInstanceId(string instanceId)
     {
         var deconstructed = instanceId.Split("/");
-        int instanceOwnerPartyId = int.Parse(deconstructed[0]);
+        int instanceOwnerPartyId = int.Parse(deconstructed[0], CultureInfo.InvariantCulture);
         Guid instanceGuid = Guid.Parse(deconstructed[1]);
 
         return (instanceOwnerPartyId, instanceGuid);
@@ -129,13 +130,17 @@ private static (int InstanceOwnerId, Guid InstanceOwnerGuid) DeconstructInstance
         string searchForSingular = "/instance/";
         string instanceSubpath = string.Empty;
 
-        if (url.Contains(searchForPlural, StringComparison.InvariantCultureIgnoreCase))
+        if (url.Contains(searchForPlural, StringComparison.OrdinalIgnoreCase))
         {
-            instanceSubpath = url.Substring(url.IndexOf(searchForPlural) + searchForPlural.Length);
+            instanceSubpath = url.Substring(
+                url.IndexOf(searchForPlural, StringComparison.OrdinalIgnoreCase) + searchForPlural.Length
+            );
         }
-        else if (url.Contains(searchForSingular, StringComparison.InvariantCultureIgnoreCase))
+        else if (url.Contains(searchForSingular, StringComparison.OrdinalIgnoreCase))
         {
-            instanceSubpath = url.Substring(url.IndexOf(searchForSingular) + searchForSingular.Length);
+            instanceSubpath = url.Substring(
+                url.IndexOf(searchForSingular, StringComparison.OrdinalIgnoreCase) + searchForSingular.Length
+            );
         }
 
         if (string.IsNullOrEmpty(instanceSubpath))
diff --git a/src/Directory.Build.props b/src/Directory.Build.props
index 6669928bf..5dff295a1 100644
--- a/src/Directory.Build.props
+++ b/src/Directory.Build.props
@@ -13,6 +13,7 @@
   </ItemGroup>
 
   <PropertyGroup>
+    <AnalysisMode>Recommended</AnalysisMode>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <EnforceCodeStyleInBuild>true</EnforceCodeStyleInBuild>
@@ -50,4 +51,4 @@
   <PropertyGroup Condition="'$(Deterministic)'=='true'">
     <ContinuousIntegrationBuild>true</ContinuousIntegrationBuild>
   </PropertyGroup>
-</Project>
\ No newline at end of file
+</Project>