diff --git a/README.md b/README.md
index cdd5dc8a..f638315c 100644
--- a/README.md
+++ b/README.md
@@ -313,7 +313,7 @@ Node-specific support is maintained in a [separate repository](https://github.co
 * [fastjsonschema](https://github.com/seznam/python-fastjsonschema)
 * [hypothesis-jsonschema](https://github.com/Zac-HD/hypothesis-jsonschema)
 * [jschon](https://github.com/marksparkza/jschon)
-* [python-experimental, OpenAPI Generator](https://github.com/OpenAPITools/openapi-generator/blob/master/docs/generators/python-experimental.md)
+* [OpenAPI JSON Schema Generator](https://github.com/openapi-json-schema-tools/openapi-json-schema-generator)
 
 ### Ruby
 
diff --git a/tests/draft-next/dependentSchemas.json b/tests/draft-next/dependentSchemas.json
index 8a847759..86079c34 100644
--- a/tests/draft-next/dependentSchemas.json
+++ b/tests/draft-next/dependentSchemas.json
@@ -132,6 +132,7 @@
     {
         "description": "dependent subschema incompatible with root",
         "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
             "properties": {
                 "foo": {}
             },
diff --git a/tests/draft-next/ref.json b/tests/draft-next/ref.json
index 1d5f2561..8417ce29 100644
--- a/tests/draft-next/ref.json
+++ b/tests/draft-next/ref.json
@@ -862,6 +862,7 @@
     {
         "description": "URN ref with nested pointer ref",
         "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
             "$ref": "urn:uuid:deadbeef-4321-ffff-ffff-1234feebdaed",
             "$defs": {
                 "foo": {
@@ -887,6 +888,7 @@
     {
         "description": "ref to if",
         "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
             "$ref": "http://example.com/ref/if",
             "if": {
                 "$id": "http://example.com/ref/if",
@@ -909,6 +911,7 @@
     {
         "description": "ref to then",
         "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
             "$ref": "http://example.com/ref/then",
             "then": {
                 "$id": "http://example.com/ref/then",
@@ -931,6 +934,7 @@
     {
         "description": "ref to else",
         "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
             "$ref": "http://example.com/ref/else",
             "else": {
                 "$id": "http://example.com/ref/else",
@@ -953,6 +957,7 @@
     {
         "description": "ref with absolute-path-reference",
         "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
             "$id": "http://example.com/ref/absref.json",
             "$defs": {
                 "a": {
@@ -982,6 +987,7 @@
     {
         "description": "$id with file URI still resolves pointers - *nix",
         "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
             "$id": "file:///folder/file.json",
             "$defs": {
                 "foo": {
@@ -1006,6 +1012,7 @@
     {
         "description": "$id with file URI still resolves pointers - windows",
         "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
             "$id": "file:///c:/folder/file.json",
             "$defs": {
                 "foo": {
@@ -1030,6 +1037,7 @@
     {
         "description": "empty tokens in $ref json-pointer",
         "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
             "$defs": {
                 "": {
                     "$defs": {
diff --git a/tests/draft-next/refRemote.json b/tests/draft-next/refRemote.json
index 9befceb2..6b7b7900 100644
--- a/tests/draft-next/refRemote.json
+++ b/tests/draft-next/refRemote.json
@@ -265,7 +265,10 @@
     },
     {
         "description": "remote HTTP ref with different $id",
-        "schema": {"$ref": "http://localhost:1234/different-id-ref-string.json"},
+        "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
+            "$ref": "http://localhost:1234/different-id-ref-string.json"
+        },
         "tests": [
             {
                 "description": "number is invalid",
@@ -281,7 +284,10 @@
     },
     {
         "description": "remote HTTP ref with different URN $id",
-        "schema": {"$ref": "http://localhost:1234/urn-ref-string.json"},
+        "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
+            "$ref": "http://localhost:1234/urn-ref-string.json"
+        },
         "tests": [
             {
                 "description": "number is invalid",
@@ -297,7 +303,10 @@
     },
     {
         "description": "remote HTTP ref with nested absolute ref",
-        "schema": {"$ref": "http://localhost:1234/nested-absolute-ref-to-string.json"},
+        "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
+            "$ref": "http://localhost:1234/nested-absolute-ref-to-string.json"
+        },
         "tests": [
             {
                 "description": "number is invalid",
@@ -314,6 +323,7 @@
     {
        "description": "$ref to $ref finds detached $anchor",
         "schema": {
+            "$schema": "https://json-schema.org/draft/next/schema",
             "$ref": "http://localhost:1234/draft-next/detached-ref.json#/$defs/foo"
         },
         "tests": [
diff --git a/tests/draft2019-09/dependentSchemas.json b/tests/draft2019-09/dependentSchemas.json
index 3577efdf..c5b8ea05 100644
--- a/tests/draft2019-09/dependentSchemas.json
+++ b/tests/draft2019-09/dependentSchemas.json
@@ -132,6 +132,7 @@
     {
         "description": "dependent subschema incompatible with root",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
             "properties": {
                 "foo": {}
             },
diff --git a/tests/draft2019-09/ref.json b/tests/draft2019-09/ref.json
index 7d850414..ea569908 100644
--- a/tests/draft2019-09/ref.json
+++ b/tests/draft2019-09/ref.json
@@ -862,6 +862,7 @@
     {
         "description": "URN ref with nested pointer ref",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
             "$ref": "urn:uuid:deadbeef-4321-ffff-ffff-1234feebdaed",
             "$defs": {
                 "foo": {
@@ -887,6 +888,7 @@
     {
         "description": "ref to if",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
             "$ref": "http://example.com/ref/if",
             "if": {
                 "$id": "http://example.com/ref/if",
@@ -909,6 +911,7 @@
     {
         "description": "ref to then",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
             "$ref": "http://example.com/ref/then",
             "then": {
                 "$id": "http://example.com/ref/then",
@@ -931,6 +934,7 @@
     {
         "description": "ref to else",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
             "$ref": "http://example.com/ref/else",
             "else": {
                 "$id": "http://example.com/ref/else",
@@ -953,6 +957,7 @@
     {
          "description": "ref with absolute-path-reference",
          "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
              "$id": "http://example.com/ref/absref.json",
              "$defs": {
                  "a": {
@@ -982,6 +987,7 @@
      {
          "description": "$id with file URI still resolves pointers - *nix",
          "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
              "$id": "file:///folder/file.json",
              "$defs": {
                  "foo": {
@@ -1006,6 +1012,7 @@
      {
          "description": "$id with file URI still resolves pointers - windows",
          "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
              "$id": "file:///c:/folder/file.json",
              "$defs": {
                  "foo": {
@@ -1030,6 +1037,7 @@
      {
          "description": "empty tokens in $ref json-pointer",
          "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
              "$defs": {
                  "": {
                      "$defs": {
diff --git a/tests/draft2019-09/refRemote.json b/tests/draft2019-09/refRemote.json
index 0bacbfc2..e1ba40ab 100644
--- a/tests/draft2019-09/refRemote.json
+++ b/tests/draft2019-09/refRemote.json
@@ -265,7 +265,10 @@
     },
     {
         "description": "remote HTTP ref with different $id",
-        "schema": {"$ref": "http://localhost:1234/different-id-ref-string.json"},
+        "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
+            "$ref": "http://localhost:1234/different-id-ref-string.json"
+        },
         "tests": [
             {
                 "description": "number is invalid",
@@ -281,7 +284,10 @@
     },
     {
         "description": "remote HTTP ref with different URN $id",
-        "schema": {"$ref": "http://localhost:1234/urn-ref-string.json"},
+        "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
+            "$ref": "http://localhost:1234/urn-ref-string.json"
+        },
         "tests": [
             {
                 "description": "number is invalid",
@@ -297,7 +303,10 @@
     },
     {
         "description": "remote HTTP ref with nested absolute ref",
-        "schema": {"$ref": "http://localhost:1234/nested-absolute-ref-to-string.json"},
+        "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
+            "$ref": "http://localhost:1234/nested-absolute-ref-to-string.json"
+        },
         "tests": [
             {
                 "description": "number is invalid",
@@ -314,6 +323,7 @@
     {
        "description": "$ref to $ref finds detached $anchor",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2019-09/schema",
             "$ref": "http://localhost:1234/draft2019-09/detached-ref.json#/$defs/foo"
         },
         "tests": [
diff --git a/tests/draft2020-12/dependentSchemas.json b/tests/draft2020-12/dependentSchemas.json
index 66ac0eb4..1c5f0574 100644
--- a/tests/draft2020-12/dependentSchemas.json
+++ b/tests/draft2020-12/dependentSchemas.json
@@ -132,6 +132,7 @@
     {
         "description": "dependent subschema incompatible with root",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
             "properties": {
                 "foo": {}
             },
diff --git a/tests/draft2020-12/ref.json b/tests/draft2020-12/ref.json
index 5f6be8c2..8d15fa43 100644
--- a/tests/draft2020-12/ref.json
+++ b/tests/draft2020-12/ref.json
@@ -862,6 +862,7 @@
     {
         "description": "URN ref with nested pointer ref",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
             "$ref": "urn:uuid:deadbeef-4321-ffff-ffff-1234feebdaed",
             "$defs": {
                 "foo": {
@@ -887,6 +888,7 @@
     {
         "description": "ref to if",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
             "$ref": "http://example.com/ref/if",
             "if": {
                 "$id": "http://example.com/ref/if",
@@ -909,6 +911,7 @@
     {
         "description": "ref to then",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
             "$ref": "http://example.com/ref/then",
             "then": {
                 "$id": "http://example.com/ref/then",
@@ -931,6 +934,7 @@
     {
         "description": "ref to else",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
             "$ref": "http://example.com/ref/else",
             "else": {
                 "$id": "http://example.com/ref/else",
@@ -953,6 +957,7 @@
     {
         "description": "ref with absolute-path-reference",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
             "$id": "http://example.com/ref/absref.json",
             "$defs": {
                 "a": {
@@ -982,6 +987,7 @@
     {
         "description": "$id with file URI still resolves pointers - *nix",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
             "$id": "file:///folder/file.json",
             "$defs": {
                 "foo": {
@@ -1006,6 +1012,7 @@
     {
         "description": "$id with file URI still resolves pointers - windows",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
             "$id": "file:///c:/folder/file.json",
             "$defs": {
                 "foo": {
@@ -1030,6 +1037,7 @@
     {
         "description": "empty tokens in $ref json-pointer",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
             "$defs": {
                 "": {
                     "$defs": {
diff --git a/tests/draft2020-12/refRemote.json b/tests/draft2020-12/refRemote.json
index ea4177f0..176eb2f5 100644
--- a/tests/draft2020-12/refRemote.json
+++ b/tests/draft2020-12/refRemote.json
@@ -265,7 +265,10 @@
     },
     {
         "description": "remote HTTP ref with different $id",
-        "schema": {"$ref": "http://localhost:1234/different-id-ref-string.json"},
+        "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
+            "$ref": "http://localhost:1234/different-id-ref-string.json"
+        },
         "tests": [
             {
                 "description": "number is invalid",
@@ -281,7 +284,10 @@
     },
     {
         "description": "remote HTTP ref with different URN $id",
-        "schema": {"$ref": "http://localhost:1234/urn-ref-string.json"},
+        "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
+            "$ref": "http://localhost:1234/urn-ref-string.json"
+        },
         "tests": [
             {
                 "description": "number is invalid",
@@ -297,7 +303,10 @@
     },
     {
         "description": "remote HTTP ref with nested absolute ref",
-        "schema": {"$ref": "http://localhost:1234/nested-absolute-ref-to-string.json"},
+        "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
+            "$ref": "http://localhost:1234/nested-absolute-ref-to-string.json"
+        },
         "tests": [
             {
                 "description": "number is invalid",
@@ -314,6 +323,7 @@
     {
         "description": "$ref to $ref finds detached $anchor",
         "schema": {
+            "$schema": "https://json-schema.org/draft/2020-12/schema",
             "$ref": "http://localhost:1234/draft2020-12/detached-ref.json#/$defs/foo"
         },
         "tests": [