diff --git a/pkg/builder3/openapi.go b/pkg/builder3/openapi.go
index e59844786..081dae306 100644
--- a/pkg/builder3/openapi.go
+++ b/pkg/builder3/openapi.go
@@ -326,6 +326,9 @@ func BuildOpenAPISpecFromRoutes(webServices []common.RouteContainer, config *com
 	if err != nil {
 		return nil, err
 	}
+	if config.PostProcessSpec != nil {
+		return config.PostProcessSpec(a.spec)
+	}
 	return a.spec, nil
 }
 
diff --git a/pkg/builder3/openapi_test.go b/pkg/builder3/openapi_test.go
index 381307167..d75c8c0ed 100644
--- a/pkg/builder3/openapi_test.go
+++ b/pkg/builder3/openapi_test.go
@@ -436,6 +436,11 @@ func TestBuildOpenAPISpec(t *testing.T) {
 				Description: "Test API",
 				Version:     "unversioned",
 			},
+			VendorExtensible: spec.VendorExtensible{
+				Extensions: map[string]any{
+					"hello": "world", // set from PostProcessSpec callback
+				},
+			},
 		},
 		Version: "3.0.0",
 		Paths: &spec3.Paths{
@@ -451,6 +456,12 @@ func TestBuildOpenAPISpec(t *testing.T) {
 			},
 		},
 	}
+	config.PostProcessSpec = func(s *spec3.OpenAPI) (*spec3.OpenAPI, error) {
+		s.Info.Extensions = map[string]any{
+			"hello": "world",
+		}
+		return s, nil
+	}
 	swagger, err := BuildOpenAPISpec(container.RegisteredWebServices(), config)
 	if !assert.NoError(err) {
 		return
diff --git a/pkg/common/common.go b/pkg/common/common.go
index 2e15e163c..e4ce843b0 100644
--- a/pkg/common/common.go
+++ b/pkg/common/common.go
@@ -164,6 +164,9 @@ type OpenAPIV3Config struct {
 	// It is an optional function to customize model names.
 	GetDefinitionName func(name string) (string, spec.Extensions)
 
+	// PostProcessSpec runs after the spec is ready to serve. It allows a final modification to the spec before serving.
+	PostProcessSpec func(*spec3.OpenAPI) (*spec3.OpenAPI, error)
+
 	// SecuritySchemes is list of all security schemes for OpenAPI service.
 	SecuritySchemes spec3.SecuritySchemes