diff --git a/vocabulary/format-assertion/src/main/java/io/github/sebastiantoepfer/jsonschema/vocabulary/formatassertion/Formats.java b/vocabulary/format-assertion/src/main/java/io/github/sebastiantoepfer/jsonschema/vocabulary/formatassertion/Formats.java
index 242df9f..19b744e 100644
--- a/vocabulary/format-assertion/src/main/java/io/github/sebastiantoepfer/jsonschema/vocabulary/formatassertion/Formats.java
+++ b/vocabulary/format-assertion/src/main/java/io/github/sebastiantoepfer/jsonschema/vocabulary/formatassertion/Formats.java
@@ -44,7 +44,9 @@ final class Formats {
         Map.entry("ipv4", Map.entry(2673, "dotted-quad")),
         Map.entry("uuid", Map.entry(4122, "UUID")),
         Map.entry("ipv6", Map.entry(4291, "IPv6address")),
-        Map.entry("json-pointer", Map.entry(6901, "json-pointer"))
+        Map.entry("json-pointer", Map.entry(6901, "json-pointer")),
+        Map.entry("iri", Map.entry(3987, "IRI")),
+        Map.entry("iri-reference", Map.entry(3987, "IRI-reference"))
     );
 
     Format findByName(final String name) {
@@ -54,7 +56,6 @@ Format findByName(final String name) {
             )
             .map(Format.class::cast)
             .or(() -> Optional.ofNullable(CUSTOM_FORMAT.get(name)))
-            .map(Format.class::cast)
             .orElseGet(() -> new UnknownFormat(name));
     }
 }
diff --git a/vocabulary/format-assertion/src/main/java/io/github/sebastiantoepfer/jsonschema/vocabulary/formatassertion/rfc/Rfcs.java b/vocabulary/format-assertion/src/main/java/io/github/sebastiantoepfer/jsonschema/vocabulary/formatassertion/rfc/Rfcs.java
index d7f5366..6cd1b69 100644
--- a/vocabulary/format-assertion/src/main/java/io/github/sebastiantoepfer/jsonschema/vocabulary/formatassertion/rfc/Rfcs.java
+++ b/vocabulary/format-assertion/src/main/java/io/github/sebastiantoepfer/jsonschema/vocabulary/formatassertion/rfc/Rfcs.java
@@ -192,6 +192,155 @@ public final class Rfcs {
                 )
             )
         ),
+        Map.entry(
+            3987,
+            Map.of(
+                "IRI",
+                new RegExRule(
+                    Pattern.compile(
+                        "^[a-z](?:[-a-z0-9\\+\\.])*:(?:\\/\\/(?:(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}" +
+                        "\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-" +
+                        "\\x{3FFFD}\\x{40000}-\\x{4FFFD}\\x{50000}-\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-" +
+                        "\\x{7FFFD}\\x{80000}-\\x{8FFFD}\\x{90000}-\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-" +
+                        "\\x{BFFFD}\\x{C0000}-\\x{CFFFD}\\x{D0000}-\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+," +
+                        ";=:])*@)?(?:\\[(?:(?:(?:[0-9a-f]{1,4}:){6}(?:[0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d" +
+                        "|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3})|::(?:[0-9a-" +
+                        "f]{1,4}:){5}(?:[0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(" +
+                        "?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3})|(?:[0-9a-f]{1,4})?::(?:[0-9a-f]{1,4}:){4}(?:[" +
+                        "0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:\\d|[1-9]\\d|1" +
+                        "\\d\\d|2[0-4]\\d|25[0-5])){3})|(?:(?:[0-9a-f]{1,4}:){0,1}[0-9a-f]{1,4})?::(?:[0-9a-f]{1,4}:)" +
+                        "{3}(?:[0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:\\d|[1-" +
+                        "9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3})|(?:(?:[0-9a-f]{1,4}:){0,2}[0-9a-f]{1,4})?::(?:[0-9a-f]" +
+                        "{1,4}:){2}(?:[0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:" +
+                        "\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3})|(?:(?:[0-9a-f]{1,4}:){0,3}[0-9a-f]{1,4})?::[0-9" +
+                        "a-f]{1,4}:(?:[0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:" +
+                        "\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3})|(?:(?:[0-9a-f]{1,4}:){0,4}[0-9a-f]{1,4})?::(?:[" +
+                        "0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:\\d|[1-9]\\d|1" +
+                        "\\d\\d|2[0-4]\\d|25[0-5])){3})|(?:(?:[0-9a-f]{1,4}:){0,5}[0-9a-f]{1,4})?::[0-9a-f]{1,4}|(?:(" +
+                        "?:[0-9a-f]{1,4}:){0,6}[0-9a-f]{1,4})?::)|v[0-9a-f]+\\.[-a-z0-9\\._~!\\$&'\\(\\)\\*\\+,;=:]+)" +
+                        "\\]|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5" +
+                        "])){3}|(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-" +
+                        "\\x{FFEF}\\x{10000}-\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-" +
+                        "\\x{4FFFD}\\x{50000}-\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-" +
+                        "\\x{8FFFD}\\x{90000}-\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-" +
+                        "\\x{CFFFD}\\x{D0000}-\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=])*)(?::\\d*)?(?:" +
+                        "\\/(?:(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-" +
+                        "\\x{FFEF}\\x{10000}-\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-" +
+                        "\\x{4FFFD}\\x{50000}-\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-" +
+                        "\\x{8FFFD}\\x{90000}-\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-" +
+                        "\\x{CFFFD}\\x{D0000}-\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@]))*)*|\\/(?:(?:(" +
+                        "?:(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}" +
+                        "\\x{10000}-\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-\\x{4FFFD}" +
+                        "\\x{50000}-\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-\\x{8FFFD}" +
+                        "\\x{90000}-\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-\\x{CFFFD}" +
+                        "\\x{D0000}-\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@]))+)(?:\\/(?:(?:%[0-9a-f][" +
+                        "0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-" +
+                        "\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-\\x{4FFFD}\\x{50000}-" +
+                        "\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-\\x{8FFFD}\\x{90000}-" +
+                        "\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-\\x{CFFFD}\\x{D0000}-" +
+                        "\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@]))*)*)?|(?:(?:(?:%[0-9a-f][0-9a-f]|[-" +
+                        "a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-\\x{1FFFD}" +
+                        "\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-\\x{4FFFD}\\x{50000}-\\x{5FFFD}" +
+                        "\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-\\x{8FFFD}\\x{90000}-\\x{9FFFD}" +
+                        "\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-\\x{CFFFD}\\x{D0000}-\\x{DFFFD}" +
+                        "\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@]))+)(?:\\/(?:(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~" +
+                        "\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-\\x{1FFFD}\\x{20000}-" +
+                        "\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-\\x{4FFFD}\\x{50000}-\\x{5FFFD}\\x{60000}-" +
+                        "\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-\\x{8FFFD}\\x{90000}-\\x{9FFFD}\\x{A0000}-" +
+                        "\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-\\x{CFFFD}\\x{D0000}-\\x{DFFFD}\\x{E1000}-" +
+                        "\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@]))*)*|(?!(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-" +
+                        "\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-\\x{1FFFD}\\x{20000}-\\x{2FFFD}" +
+                        "\\x{30000}-\\x{3FFFD}\\x{40000}-\\x{4FFFD}\\x{50000}-\\x{5FFFD}\\x{60000}-\\x{6FFFD}" +
+                        "\\x{70000}-\\x{7FFFD}\\x{80000}-\\x{8FFFD}\\x{90000}-\\x{9FFFD}\\x{A0000}-\\x{AFFFD}" +
+                        "\\x{B0000}-\\x{BFFFD}\\x{C0000}-\\x{CFFFD}\\x{D0000}-\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\" +
+                        "(\\)\\*\\+,;=:@])))(?:\\?(?:(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-" +
+                        "\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}" +
+                        "\\x{40000}-\\x{4FFFD}\\x{50000}-\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}" +
+                        "\\x{80000}-\\x{8FFFD}\\x{90000}-\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}" +
+                        "\\x{C0000}-\\x{CFFFD}\\x{D0000}-\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@])|[" +
+                        "\\x{E000}-\\x{F8FF}\\x{F0000}-\\x{FFFFD}\\x{100000}-\\x{10FFFD}\\/\\?])*)?(?:\\#(?:(?:%[0-9a" +
+                        "-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-" +
+                        "\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-\\x{4FFFD}\\x{50000}-" +
+                        "\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-\\x{8FFFD}\\x{90000}-" +
+                        "\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-\\x{CFFFD}\\x{D0000}-" +
+                        "\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@])|[\\/\\?])*)?$",
+                        Pattern.CASE_INSENSITIVE
+                    )
+                ),
+                "IRI-reference",
+                new RegExRule(
+                    Pattern.compile(
+                        "^[a-z](?:[-a-z0-9\\+\\.])*:(?:\\/\\/(?:(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}" +
+                        "\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-" +
+                        "\\x{3FFFD}\\x{40000}-\\x{4FFFD}\\x{50000}-\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-" +
+                        "\\x{7FFFD}\\x{80000}-\\x{8FFFD}\\x{90000}-\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-" +
+                        "\\x{BFFFD}\\x{C0000}-\\x{CFFFD}\\x{D0000}-\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+," +
+                        ";=:])*@)?(?:\\[(?:(?:(?:[0-9a-f]{1,4}:){6}(?:[0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d" +
+                        "|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3})|::(?:[0-9a-" +
+                        "f]{1,4}:){5}(?:[0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(" +
+                        "?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3})|(?:[0-9a-f]{1,4})?::(?:[0-9a-f]{1,4}:){4}(?:[" +
+                        "0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:\\d|[1-9]\\d|1" +
+                        "\\d\\d|2[0-4]\\d|25[0-5])){3})|(?:(?:[0-9a-f]{1,4}:){0,1}[0-9a-f]{1,4})?::(?:[0-9a-f]{1,4}:)" +
+                        "{3}(?:[0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:\\d|[1-" +
+                        "9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3})|(?:(?:[0-9a-f]{1,4}:){0,2}[0-9a-f]{1,4})?::(?:[0-9a-f]" +
+                        "{1,4}:){2}(?:[0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:" +
+                        "\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3})|(?:(?:[0-9a-f]{1,4}:){0,3}[0-9a-f]{1,4})?::[0-9" +
+                        "a-f]{1,4}:(?:[0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:" +
+                        "\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3})|(?:(?:[0-9a-f]{1,4}:){0,4}[0-9a-f]{1,4})?::(?:[" +
+                        "0-9a-f]{1,4}:[0-9a-f]{1,4}|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:\\d|[1-9]\\d|1" +
+                        "\\d\\d|2[0-4]\\d|25[0-5])){3})|(?:(?:[0-9a-f]{1,4}:){0,5}[0-9a-f]{1,4})?::[0-9a-f]{1,4}|(?:(" +
+                        "?:[0-9a-f]{1,4}:){0,6}[0-9a-f]{1,4})?::)|v[0-9a-f]+\\.[-a-z0-9\\._~!\\$&'\\(\\)\\*\\+,;=:]+)" +
+                        "\\]|(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])(?:\\.(?:\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5" +
+                        "])){3}|(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-" +
+                        "\\x{FFEF}\\x{10000}-\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-" +
+                        "\\x{4FFFD}\\x{50000}-\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-" +
+                        "\\x{8FFFD}\\x{90000}-\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-" +
+                        "\\x{CFFFD}\\x{D0000}-\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=])*)(?::\\d*)?(?:" +
+                        "\\/(?:(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-" +
+                        "\\x{FFEF}\\x{10000}-\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-" +
+                        "\\x{4FFFD}\\x{50000}-\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-" +
+                        "\\x{8FFFD}\\x{90000}-\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-" +
+                        "\\x{CFFFD}\\x{D0000}-\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@]))*)*|\\/(?:(?:(" +
+                        "?:(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}" +
+                        "\\x{10000}-\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-\\x{4FFFD}" +
+                        "\\x{50000}-\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-\\x{8FFFD}" +
+                        "\\x{90000}-\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-\\x{CFFFD}" +
+                        "\\x{D0000}-\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@]))+)(?:\\/(?:(?:%[0-9a-f][" +
+                        "0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-" +
+                        "\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-\\x{4FFFD}\\x{50000}-" +
+                        "\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-\\x{8FFFD}\\x{90000}-" +
+                        "\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-\\x{CFFFD}\\x{D0000}-" +
+                        "\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@]))*)*)?|(?:(?:(?:%[0-9a-f][0-9a-f]|[-" +
+                        "a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-\\x{1FFFD}" +
+                        "\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-\\x{4FFFD}\\x{50000}-\\x{5FFFD}" +
+                        "\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-\\x{8FFFD}\\x{90000}-\\x{9FFFD}" +
+                        "\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-\\x{CFFFD}\\x{D0000}-\\x{DFFFD}" +
+                        "\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@]))+)(?:\\/(?:(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~" +
+                        "\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-\\x{1FFFD}\\x{20000}-" +
+                        "\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-\\x{4FFFD}\\x{50000}-\\x{5FFFD}\\x{60000}-" +
+                        "\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-\\x{8FFFD}\\x{90000}-\\x{9FFFD}\\x{A0000}-" +
+                        "\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-\\x{CFFFD}\\x{D0000}-\\x{DFFFD}\\x{E1000}-" +
+                        "\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@]))*)*|(?!(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-" +
+                        "\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-\\x{1FFFD}\\x{20000}-\\x{2FFFD}" +
+                        "\\x{30000}-\\x{3FFFD}\\x{40000}-\\x{4FFFD}\\x{50000}-\\x{5FFFD}\\x{60000}-\\x{6FFFD}" +
+                        "\\x{70000}-\\x{7FFFD}\\x{80000}-\\x{8FFFD}\\x{90000}-\\x{9FFFD}\\x{A0000}-\\x{AFFFD}" +
+                        "\\x{B0000}-\\x{BFFFD}\\x{C0000}-\\x{CFFFD}\\x{D0000}-\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\" +
+                        "(\\)\\*\\+,;=:@])))(?:\\?(?:(?:%[0-9a-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-" +
+                        "\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}" +
+                        "\\x{40000}-\\x{4FFFD}\\x{50000}-\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}" +
+                        "\\x{80000}-\\x{8FFFD}\\x{90000}-\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}" +
+                        "\\x{C0000}-\\x{CFFFD}\\x{D0000}-\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@])|[" +
+                        "\\x{E000}-\\x{F8FF}\\x{F0000}-\\x{FFFFD}\\x{100000}-\\x{10FFFD}\\/\\?])*)?(?:\\#(?:(?:%[0-9a" +
+                        "-f][0-9a-f]|[-a-z0-9\\._~\\x{A0}-\\x{D7FF}\\x{F900}-\\x{FDCF}\\x{FDF0}-\\x{FFEF}\\x{10000}-" +
+                        "\\x{1FFFD}\\x{20000}-\\x{2FFFD}\\x{30000}-\\x{3FFFD}\\x{40000}-\\x{4FFFD}\\x{50000}-" +
+                        "\\x{5FFFD}\\x{60000}-\\x{6FFFD}\\x{70000}-\\x{7FFFD}\\x{80000}-\\x{8FFFD}\\x{90000}-" +
+                        "\\x{9FFFD}\\x{A0000}-\\x{AFFFD}\\x{B0000}-\\x{BFFFD}\\x{C0000}-\\x{CFFFD}\\x{D0000}-" +
+                        "\\x{DFFFD}\\x{E1000}-\\x{EFFFD}!\\$&'\\(\\)\\*\\+,;=:@])|[\\/\\?])*)?$",
+                        Pattern.CASE_INSENSITIVE
+                    )
+                )
+            )
+        ),
         Map.entry(
             4122,
             Map.of(
@@ -265,7 +414,7 @@ public final class Rfcs {
                 new RegExRule(
                     Pattern.compile(
                         "(([!#-$&-;=?-\\[\\]_a-z~\\xa0-\\ud7ff\\uf900-\\ufdcf\\ufdf0-\\uffef\\ue000-\\uf8ff]|%[0-9A-F" +
-                        "a-f][0-9A-Fa-f])|\\{[+#./;?&=,!@|]?(\\w|%[0-9A-Fa-f][0-9A-Fa-f])((\\.)?([a-zA-Z0-9_]|%[0-9A-" +
+                        "a-f][0-9A-Fa-f])|\\{[+#./;?&=,!@|]?(\\w|%[0-9A-Fa-f][0-9A-Fa-f])((\\.)?(\\w|%[0-9A-" +
                         "Fa-f][0-9A-Fa-f]))*(:[1-9]\\d{0,3}|\\*)?(,(\\w|%[0-9A-Fa-f][0-9A-Fa-f])((\\.)?(\\w|%[0-9A-Fa" +
                         "-f][0-9A-Fa-f]))*(:[1-9]\\d{0,3}|\\*)?)*\\})*"
                     )
diff --git a/vocabulary/format-assertion/src/test/java/io/github/sebastiantoepfer/jsonschema/vocabulary/formatassertion/FormatsTest.java b/vocabulary/format-assertion/src/test/java/io/github/sebastiantoepfer/jsonschema/vocabulary/formatassertion/FormatsTest.java
index 731f6f2..3e10701 100644
--- a/vocabulary/format-assertion/src/test/java/io/github/sebastiantoepfer/jsonschema/vocabulary/formatassertion/FormatsTest.java
+++ b/vocabulary/format-assertion/src/test/java/io/github/sebastiantoepfer/jsonschema/vocabulary/formatassertion/FormatsTest.java
@@ -142,4 +142,19 @@ void should_found_regexformat() {
         assertThat(new Formats().findByName("regex").applyTo("^[0-9]*"), is(true));
         assertThat(new Formats().findByName("regex").applyTo("({"), is(false));
     }
+
+    @Test
+    void should_found_iriformat() {
+        //α -> only looks like an a, but is not one
+        assertThat(new Formats().findByName("iri").applyTo("http://www.myfictionαlbank.com"), is(true));
+        assertThat(new Formats().findByName("iri").applyTo("mailto:somebody@google.com"), is(true));
+        assertThat(new Formats().findByName("iri").applyTo("1://noIri"), is(false));
+    }
+
+    @Test
+    void should_found_irireferenceformat() {
+        //α -> only looks like an a, but is not one
+        assertThat(new Formats().findByName("iri-reference").applyTo("http://www.myfictionαlbank.com"), is(true));
+        assertThat(new Formats().findByName("iri-reference").applyTo("1://noIri"), is(false));
+    }
 }