diff --git a/payload-schemas/api.github.com/check_run/completed.schema.json b/payload-schemas/api.github.com/check_run/completed.schema.json
index e8803cde6..664bb76a5 100644
--- a/payload-schemas/api.github.com/check_run/completed.schema.json
+++ b/payload-schemas/api.github.com/check_run/completed.schema.json
@@ -57,10 +57,12 @@
         },
         "started_at": {
           "type": "string",
+          "format": "date-time",
           "description": "The time that the check run began. This is a timestamp in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format: `YYYY-MM-DDTHH:MM:SSZ`."
         },
         "completed_at": {
           "type": "string",
+          "format": "date-time",
           "description": "The time the check completed. This is a timestamp in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format: `YYYY-MM-DDTHH:MM:SSZ`."
         },
         "output": {
diff --git a/payload-schemas/api.github.com/check_run/created.schema.json b/payload-schemas/api.github.com/check_run/created.schema.json
index 6de66c44d..7a970a8d5 100644
--- a/payload-schemas/api.github.com/check_run/created.schema.json
+++ b/payload-schemas/api.github.com/check_run/created.schema.json
@@ -57,10 +57,14 @@
         },
         "started_at": {
           "type": "string",
+          "format": "date-time",
           "description": "The time that the check run began. This is a timestamp in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format: `YYYY-MM-DDTHH:MM:SSZ`."
         },
         "completed_at": {
-          "type": ["string", "null"],
+          "oneOf": [
+            {"type": "null"},
+            {"type": "string", "format": "date-time"}
+          ],
           "description": "The time the check completed. This is a timestamp in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format: `YYYY-MM-DDTHH:MM:SSZ`."
         },
         "output": {
diff --git a/payload-schemas/api.github.com/check_run/requested_action.schema.json b/payload-schemas/api.github.com/check_run/requested_action.schema.json
index b4d848b2b..98cfb5aa1 100644
--- a/payload-schemas/api.github.com/check_run/requested_action.schema.json
+++ b/payload-schemas/api.github.com/check_run/requested_action.schema.json
@@ -63,10 +63,14 @@
         },
         "started_at": {
           "type": "string",
+          "format": "date-time",
           "description": "The time that the check run began. This is a timestamp in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format: `YYYY-MM-DDTHH:MM:SSZ`."
         },
         "completed_at": {
-          "type": ["string", "null"],
+          "oneOf": [
+            {"type": "null"},
+            {"type": "string", "format": "date-time"}
+          ],
           "description": "The time the check completed. This is a timestamp in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format: `YYYY-MM-DDTHH:MM:SSZ`."
         },
         "output": {
diff --git a/payload-schemas/api.github.com/check_run/rerequested.schema.json b/payload-schemas/api.github.com/check_run/rerequested.schema.json
index ff6bb05cf..2149383ac 100644
--- a/payload-schemas/api.github.com/check_run/rerequested.schema.json
+++ b/payload-schemas/api.github.com/check_run/rerequested.schema.json
@@ -57,10 +57,12 @@
         },
         "started_at": {
           "type": "string",
+          "format": "date-time",
           "description": "The time that the check run began. This is a timestamp in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format: `YYYY-MM-DDTHH:MM:SSZ`."
         },
         "completed_at": {
           "type": "string",
+          "format": "date-time",
           "description": "The time the check completed. This is a timestamp in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format: `YYYY-MM-DDTHH:MM:SSZ`."
         },
         "output": {
diff --git a/payload-schemas/api.github.com/commit_comment/created.schema.json b/payload-schemas/api.github.com/commit_comment/created.schema.json
index 521ca1483..5e9e3c4e2 100644
--- a/payload-schemas/api.github.com/commit_comment/created.schema.json
+++ b/payload-schemas/api.github.com/commit_comment/created.schema.json
@@ -56,8 +56,8 @@
           "type": "string",
           "description": "The SHA of the commit to which the comment applies."
         },
-        "created_at": { "type": "string" },
-        "updated_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
         "author_association": {
           "$ref": "common/author_association.schema.json"
         },
diff --git a/payload-schemas/api.github.com/common/deployment.schema.json b/payload-schemas/api.github.com/common/deployment.schema.json
index 4c42c93b3..5bd9f95a5 100644
--- a/payload-schemas/api.github.com/common/deployment.schema.json
+++ b/payload-schemas/api.github.com/common/deployment.schema.json
@@ -37,8 +37,8 @@
     "production_environment": { "type": "boolean" },
     "description": { "type": ["string", "null"] },
     "creator": { "$ref": "user.schema.json" },
-    "created_at": { "type": "string" },
-    "updated_at": { "type": "string" },
+    "created_at": { "type": "string", "format": "date-time" },
+    "updated_at": { "type": "string", "format": "date-time" },
     "statuses_url": { "type": "string", "format": "uri" },
     "repository_url": { "type": "string", "format": "uri" },
     "performed_via_github_app": {
diff --git a/payload-schemas/api.github.com/common/discussion.schema.json b/payload-schemas/api.github.com/common/discussion.schema.json
index 7d8eaedfa..325c1b009 100644
--- a/payload-schemas/api.github.com/common/discussion.schema.json
+++ b/payload-schemas/api.github.com/common/discussion.schema.json
@@ -45,14 +45,19 @@
         "name": { "type": "string" },
         "description": { "type": "string" },
         "created_at": { "type": "string", "format": "date-time" },
-        "updated_at": { "type": "string" },
+        "updated_at": { "type": "string", "format": "date-time" },
         "slug": { "type": "string" },
         "is_answerable": { "type": "boolean" }
       },
       "additionalProperties": false
     },
     "answer_html_url": { "type": ["string", "null"] },
-    "answer_chosen_at": { "type": ["string", "null"] },
+    "answer_chosen_at": {
+      "oneOf": [
+        {"type": "null"},
+        {"type": "string", "format": "date-time"}
+      ]
+    },
     "answer_chosen_by": {
       "oneOf": [{ "$ref": "user.schema.json" }, { "type": "null" }]
     },
diff --git a/payload-schemas/api.github.com/common/repository-vulnerability-alert-alert.schema.json b/payload-schemas/api.github.com/common/repository-vulnerability-alert-alert.schema.json
index bb3d4521f..d21c064a7 100644
--- a/payload-schemas/api.github.com/common/repository-vulnerability-alert-alert.schema.json
+++ b/payload-schemas/api.github.com/common/repository-vulnerability-alert-alert.schema.json
@@ -25,7 +25,7 @@
     "affected_package_name": { "type": "string" },
     "dismisser": { "$ref": "user.schema.json" },
     "dismiss_reason": { "type": "string" },
-    "dismissed_at": { "type": "string" },
+    "dismissed_at": { "type": "string", "format": "date-time" },
     "severity": { "type": "string" },
     "ghsa_id": { "type": "string" },
     "external_reference": { "type": "string", "format": "uri" },
@@ -33,7 +33,7 @@
     "fixed_in": { "type": "string" },
     "fixed_at": { "type": "string", "format": "date-time" },
     "fix_reason": { "type": "string" },
-    "created_at": { "type": "string" }
+    "created_at": { "type": "string", "format": "date-timme" }
   },
   "additionalProperties": false,
   "description": "The security alert of the vulnerable dependency.",
diff --git a/payload-schemas/api.github.com/common/simple-pull-request.schema.json b/payload-schemas/api.github.com/common/simple-pull-request.schema.json
index 9d2870fb4..ae6d7fbe4 100644
--- a/payload-schemas/api.github.com/common/simple-pull-request.schema.json
+++ b/payload-schemas/api.github.com/common/simple-pull-request.schema.json
@@ -54,10 +54,20 @@
     "title": { "type": "string" },
     "user": { "$ref": "user.schema.json" },
     "body": { "type": "string" },
-    "created_at": { "type": "string" },
-    "updated_at": { "type": "string" },
-    "closed_at": { "type": ["string", "null"] },
-    "merged_at": { "type": ["string", "null"] },
+    "created_at": { "type": "string", "format": "date-time" },
+    "updated_at": { "type": "string", "format": "date-time" },
+    "closed_at": {
+      "oneOf": [
+        {"type": "null"},
+        {"type": "string", "format": "date-time"}
+      ]
+    },
+    "merged_at": {
+      "oneOf": [
+        {"type": "null"},
+        {"type": "string", "format": "date-time"}
+      ]
+    },
     "merge_commit_sha": { "type": ["string", "null"] },
     "assignee": {
       "oneOf": [{ "$ref": "user.schema.json" }, { "type": "null" }]
diff --git a/payload-schemas/api.github.com/common/sponsorship-tier.schema.json b/payload-schemas/api.github.com/common/sponsorship-tier.schema.json
index 2a4351bbf..08ea2a127 100644
--- a/payload-schemas/api.github.com/common/sponsorship-tier.schema.json
+++ b/payload-schemas/api.github.com/common/sponsorship-tier.schema.json
@@ -15,7 +15,7 @@
   "type": "object",
   "properties": {
     "node_id": { "type": "string" },
-    "created_at": { "type": "string" },
+    "created_at": { "type": "string", "format": "date-time" },
     "description": { "type": "string" },
     "monthly_price_in_cents": { "type": "integer" },
     "monthly_price_in_dollars": { "type": "integer" },
diff --git a/payload-schemas/api.github.com/common/workflow-job.schema.json b/payload-schemas/api.github.com/common/workflow-job.schema.json
index 6f53dbdf7..f15cdc538 100644
--- a/payload-schemas/api.github.com/common/workflow-job.schema.json
+++ b/payload-schemas/api.github.com/common/workflow-job.schema.json
@@ -71,8 +71,13 @@
       "type": ["string", "null"],
       "description": "The name of the runner group that is running this job. This will be `null` as long as `workflow_job[status]` is `queued`."
     },
-    "started_at": { "type": "string" },
-    "completed_at": { "type": ["string", "null"] }
+    "started_at": { "type": "string", "format": "date-time" },
+    "completed_at": {
+      "oneOf": [
+        {"type": "null"},
+        {"type": "string", "format": "date-time"}
+      ]
+    }
   },
   "additionalProperties": false,
   "title": "Workflow Job"
diff --git a/payload-schemas/api.github.com/common/workflow-step-completed.schema.json b/payload-schemas/api.github.com/common/workflow-step-completed.schema.json
index 0c05621b0..f14b6d77c 100644
--- a/payload-schemas/api.github.com/common/workflow-step-completed.schema.json
+++ b/payload-schemas/api.github.com/common/workflow-step-completed.schema.json
@@ -18,8 +18,8 @@
       "enum": ["failure", "skipped", "success"]
     },
     "number": { "type": "integer" },
-    "started_at": { "type": "string" },
-    "completed_at": { "type": "string" }
+    "started_at": { "type": "string", "format": "date-time" },
+    "completed_at": { "type": "string", "format": "date-time" }
   },
   "additionalProperties": false,
   "title": "Workflow Step (Completed)"
diff --git a/payload-schemas/api.github.com/common/workflow-step-in_progress.schema.json b/payload-schemas/api.github.com/common/workflow-step-in_progress.schema.json
index dd0af41c8..6a3b118e0 100644
--- a/payload-schemas/api.github.com/common/workflow-step-in_progress.schema.json
+++ b/payload-schemas/api.github.com/common/workflow-step-in_progress.schema.json
@@ -15,7 +15,7 @@
     "status": { "type": "string", "enum": ["in_progress"] },
     "conclusion": { "type": "null" },
     "number": { "type": "integer" },
-    "started_at": { "type": "string" },
+    "started_at": { "type": "string", "format": "date-time" },
     "completed_at": { "type": "null" }
   },
   "additionalProperties": false,
diff --git a/payload-schemas/api.github.com/deploy_key/created.schema.json b/payload-schemas/api.github.com/deploy_key/created.schema.json
index 31440405c..b57a8b738 100644
--- a/payload-schemas/api.github.com/deploy_key/created.schema.json
+++ b/payload-schemas/api.github.com/deploy_key/created.schema.json
@@ -23,7 +23,7 @@
         "url": { "type": "string", "format": "uri" },
         "title": { "type": "string" },
         "verified": { "type": "boolean" },
-        "created_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
         "read_only": { "type": "boolean" }
       },
       "additionalProperties": false
diff --git a/payload-schemas/api.github.com/deploy_key/deleted.schema.json b/payload-schemas/api.github.com/deploy_key/deleted.schema.json
index 00697670b..45de2cf85 100644
--- a/payload-schemas/api.github.com/deploy_key/deleted.schema.json
+++ b/payload-schemas/api.github.com/deploy_key/deleted.schema.json
@@ -23,7 +23,7 @@
         "url": { "type": "string", "format": "uri" },
         "title": { "type": "string" },
         "verified": { "type": "boolean" },
-        "created_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
         "read_only": { "type": "boolean" }
       },
       "additionalProperties": false
diff --git a/payload-schemas/api.github.com/deployment_status/created.schema.json b/payload-schemas/api.github.com/deployment_status/created.schema.json
index 5667a183e..852206ace 100644
--- a/payload-schemas/api.github.com/deployment_status/created.schema.json
+++ b/payload-schemas/api.github.com/deployment_status/created.schema.json
@@ -53,8 +53,8 @@
           "type": "string",
           "description": "The optional link added to the status."
         },
-        "created_at": { "type": "string" },
-        "updated_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
         "deployment_url": { "type": "string", "format": "uri" },
         "repository_url": { "type": "string", "format": "uri" },
         "performed_via_github_app": {
diff --git a/payload-schemas/api.github.com/discussion/category_changed.schema.json b/payload-schemas/api.github.com/discussion/category_changed.schema.json
index eb60e13b2..b633d89d4 100644
--- a/payload-schemas/api.github.com/discussion/category_changed.schema.json
+++ b/payload-schemas/api.github.com/discussion/category_changed.schema.json
@@ -32,7 +32,7 @@
                 "name": { "type": "string" },
                 "description": { "type": "string" },
                 "created_at": { "type": "string", "format": "date-time" },
-                "updated_at": { "type": "string" },
+                "updated_at": { "type": "string", "format": "date-time" },
                 "slug": { "type": "string" },
                 "is_answerable": { "type": "boolean" }
               },
diff --git a/payload-schemas/api.github.com/discussion_comment/created.schema.json b/payload-schemas/api.github.com/discussion_comment/created.schema.json
index 16ec5b701..8b7f7e3d8 100644
--- a/payload-schemas/api.github.com/discussion_comment/created.schema.json
+++ b/payload-schemas/api.github.com/discussion_comment/created.schema.json
@@ -41,8 +41,8 @@
           "$ref": "common/author_association.schema.json"
         },
         "user": { "$ref": "common/user.schema.json" },
-        "created_at": { "type": "string" },
-        "updated_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
         "body": { "type": "string" },
         "reactions": { "$ref": "common/reactions.schema.json" }
       },
diff --git a/payload-schemas/api.github.com/discussion_comment/deleted.schema.json b/payload-schemas/api.github.com/discussion_comment/deleted.schema.json
index 7e51b79da..2844aa6d4 100644
--- a/payload-schemas/api.github.com/discussion_comment/deleted.schema.json
+++ b/payload-schemas/api.github.com/discussion_comment/deleted.schema.json
@@ -41,8 +41,8 @@
           "$ref": "common/author_association.schema.json"
         },
         "user": { "$ref": "common/user.schema.json" },
-        "created_at": { "type": "string" },
-        "updated_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
         "body": { "type": "string" },
         "reactions": { "$ref": "common/reactions.schema.json" }
       },
diff --git a/payload-schemas/api.github.com/discussion_comment/edited.schema.json b/payload-schemas/api.github.com/discussion_comment/edited.schema.json
index 98ffd1c8b..280f65057 100644
--- a/payload-schemas/api.github.com/discussion_comment/edited.schema.json
+++ b/payload-schemas/api.github.com/discussion_comment/edited.schema.json
@@ -55,8 +55,8 @@
           "$ref": "common/author_association.schema.json"
         },
         "user": { "$ref": "common/user.schema.json" },
-        "created_at": { "type": "string" },
-        "updated_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
         "body": { "type": "string" },
         "reactions": { "$ref": "common/reactions.schema.json" }
       },
diff --git a/payload-schemas/api.github.com/meta/deleted.schema.json b/payload-schemas/api.github.com/meta/deleted.schema.json
index dda0b6fbc..9ebe582cb 100644
--- a/payload-schemas/api.github.com/meta/deleted.schema.json
+++ b/payload-schemas/api.github.com/meta/deleted.schema.json
@@ -39,8 +39,8 @@
           },
           "additionalProperties": false
         },
-        "updated_at": { "type": "string" },
-        "created_at": { "type": "string" }
+        "updated_at": { "type": "string", "format": "date-time" },
+        "created_at": { "type": "string", "format": "date-time" }
       },
       "additionalProperties": false
     },
diff --git a/payload-schemas/api.github.com/package/published.schema.json b/payload-schemas/api.github.com/package/published.schema.json
index 7c4042d5c..b79b262d1 100644
--- a/payload-schemas/api.github.com/package/published.schema.json
+++ b/payload-schemas/api.github.com/package/published.schema.json
@@ -30,8 +30,8 @@
         "ecosystem": { "type": "string" },
         "package_type": { "type": "string" },
         "html_url": { "type": "string", "format": "uri" },
-        "created_at": { "type": "string" },
-        "updated_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
         "owner": { "$ref": "common/user.schema.json" },
         "package_version": {
           "type": "object",
@@ -93,8 +93,8 @@
                 "draft": { "type": "boolean" },
                 "author": { "$ref": "common/user.schema.json" },
                 "prerelease": { "type": "boolean" },
-                "created_at": { "type": "string" },
-                "published_at": { "type": "string" }
+                "created_at": { "type": "string", "format": "date-time" },
+                "published_at": { "type": "string", "format": "date-time" }
               },
               "additionalProperties": false
             },
@@ -105,8 +105,8 @@
             "target_oid": { "type": "string" },
             "draft": { "type": "boolean" },
             "prerelease": { "type": "boolean" },
-            "created_at": { "type": "string" },
-            "updated_at": { "type": "string" },
+            "created_at": { "type": "string", "format": "date-time" },
+            "updated_at": { "type": "string", "format": "date-time" },
             "metadata": { "type": "array", "items": {} },
             "docker_metadata": { "type": "array", "items": {} },
             "package_files": {
@@ -136,8 +136,8 @@
                   "content_type": { "type": "string" },
                   "state": { "type": "string" },
                   "size": { "type": "integer" },
-                  "created_at": { "type": "string" },
-                  "updated_at": { "type": "string" }
+                  "created_at": { "type": "string", "format": "date-time" },
+                  "updated_at": { "type": "string", "format": "date-time" }
                 },
                 "additionalProperties": false
               }
diff --git a/payload-schemas/api.github.com/package/updated.schema.json b/payload-schemas/api.github.com/package/updated.schema.json
index f1cd818df..0a54193a6 100644
--- a/payload-schemas/api.github.com/package/updated.schema.json
+++ b/payload-schemas/api.github.com/package/updated.schema.json
@@ -30,8 +30,8 @@
         "ecosystem": { "type": "string" },
         "package_type": { "type": "string" },
         "html_url": { "type": "string", "format": "uri" },
-        "created_at": { "type": "string" },
-        "updated_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
         "owner": { "$ref": "common/user.schema.json" },
         "package_version": {
           "type": "object",
@@ -93,8 +93,8 @@
                 "draft": { "type": "boolean" },
                 "author": { "$ref": "common/user.schema.json" },
                 "prerelease": { "type": "boolean" },
-                "created_at": { "type": "string" },
-                "published_at": { "type": "string" }
+                "created_at": { "type": "string", "format": "date-time" },
+                "published_at": { "type": "string", "format": "date-time" }
               },
               "additionalProperties": false
             },
@@ -105,8 +105,8 @@
             "target_oid": { "type": "string" },
             "draft": { "type": "boolean" },
             "prerelease": { "type": "boolean" },
-            "created_at": { "type": "string" },
-            "updated_at": { "type": "string" },
+            "created_at": { "type": "string", "format": "date-time" },
+            "updated_at": { "type": "string", "format": "date-time" },
             "metadata": { "type": "array", "items": {} },
             "docker_metadata": { "type": "array", "items": {} },
             "package_files": {
@@ -136,8 +136,8 @@
                   "content_type": { "type": "string" },
                   "state": { "type": "string" },
                   "size": { "type": "integer" },
-                  "created_at": { "type": "string" },
-                  "updated_at": { "type": "string" }
+                  "created_at": { "type": "string", "format": "date-time" },
+                  "updated_at": { "type": "string", "format": "date-time" }
                 },
                 "additionalProperties": false
               }
diff --git a/payload-schemas/api.github.com/page_build/event.schema.json b/payload-schemas/api.github.com/page_build/event.schema.json
index c872d7734..c7bcfb9b1 100644
--- a/payload-schemas/api.github.com/page_build/event.schema.json
+++ b/payload-schemas/api.github.com/page_build/event.schema.json
@@ -31,8 +31,8 @@
         "pusher": { "$ref": "common/user.schema.json" },
         "commit": { "type": "string" },
         "duration": { "type": "integer" },
-        "created_at": { "type": "string" },
-        "updated_at": { "type": "string" }
+        "created_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" }
       },
       "additionalProperties": false
     },
diff --git a/payload-schemas/api.github.com/ping/event.schema.json b/payload-schemas/api.github.com/ping/event.schema.json
index 1a08496bd..9b84a42bf 100644
--- a/payload-schemas/api.github.com/ping/event.schema.json
+++ b/payload-schemas/api.github.com/ping/event.schema.json
@@ -46,8 +46,8 @@
           },
           "additionalProperties": false
         },
-        "updated_at": { "type": "string" },
-        "created_at": { "type": "string" },
+        "updated_at": { "type": "string", "format": "date-time" },
+        "created_at": { "type": "string", "format": "date-time" },
         "url": { "type": "string", "format": "uri" },
         "test_url": { "type": "string", "format": "uri" },
         "ping_url": { "type": "string", "format": "uri" },
diff --git a/payload-schemas/api.github.com/pull_request_review_comment/created.schema.json b/payload-schemas/api.github.com/pull_request_review_comment/created.schema.json
index 175b62538..5bed95a4a 100644
--- a/payload-schemas/api.github.com/pull_request_review_comment/created.schema.json
+++ b/payload-schemas/api.github.com/pull_request_review_comment/created.schema.json
@@ -58,10 +58,20 @@
         "title": { "type": "string" },
         "user": { "$ref": "common/user.schema.json" },
         "body": { "type": "string" },
-        "created_at": { "type": "string" },
-        "updated_at": { "type": "string" },
-        "closed_at": { "type": ["string", "null"] },
-        "merged_at": { "type": ["string", "null"] },
+        "created_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
+        "closed_at": {
+          "oneOf": [
+            {"type": "null"},
+            {"type": "string", "format": "date-time"}
+          ]
+        },
+        "merged_at": {
+          "oneOf": [
+            {"type": "null"},
+            {"type": "string", "format": "date-time"}
+          ]
+        },
         "merge_commit_sha": { "type": ["string", "null"] },
         "assignee": {
           "oneOf": [{ "$ref": "common/user.schema.json" }, { "type": "null" }]
diff --git a/payload-schemas/api.github.com/pull_request_review_comment/deleted.schema.json b/payload-schemas/api.github.com/pull_request_review_comment/deleted.schema.json
index 64e5123f7..24e75f397 100644
--- a/payload-schemas/api.github.com/pull_request_review_comment/deleted.schema.json
+++ b/payload-schemas/api.github.com/pull_request_review_comment/deleted.schema.json
@@ -58,10 +58,20 @@
         "title": { "type": "string" },
         "user": { "$ref": "common/user.schema.json" },
         "body": { "type": "string" },
-        "created_at": { "type": "string" },
-        "updated_at": { "type": "string" },
-        "closed_at": { "type": ["string", "null"] },
-        "merged_at": { "type": ["string", "null"] },
+        "created_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
+        "closed_at": {
+          "oneOf": [
+            {"type": "null"},
+            {"type": "string", "format": "date-time"}
+          ]
+        },
+        "merged_at": {
+          "oneOf": [
+            {"type": "null"},
+            {"type": "string", "format": "date-time"}
+          ]
+        },
         "merge_commit_sha": { "type": ["string", "null"] },
         "assignee": {
           "oneOf": [{ "$ref": "common/user.schema.json" }, { "type": "null" }]
diff --git a/payload-schemas/api.github.com/pull_request_review_comment/edited.schema.json b/payload-schemas/api.github.com/pull_request_review_comment/edited.schema.json
index 4cbaf6f9a..ede2fabf8 100644
--- a/payload-schemas/api.github.com/pull_request_review_comment/edited.schema.json
+++ b/payload-schemas/api.github.com/pull_request_review_comment/edited.schema.json
@@ -83,10 +83,20 @@
         "title": { "type": "string" },
         "user": { "$ref": "common/user.schema.json" },
         "body": { "type": "string" },
-        "created_at": { "type": "string" },
-        "updated_at": { "type": "string" },
-        "closed_at": { "type": ["string", "null"] },
-        "merged_at": { "type": ["string", "null"] },
+        "created_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
+        "closed_at": {
+          "oneOf": [
+            {"type": "null"},
+            {"type": "string", "format": "date-time"}
+          ]
+        },
+        "merged_at": {
+          "oneOf": [
+            {"type": "null"},
+            {"type": "string", "format": "date-time"}
+          ]
+        },
         "merge_commit_sha": { "type": ["string", "null"] },
         "assignee": {
           "oneOf": [{ "$ref": "common/user.schema.json" }, { "type": "null" }]
diff --git a/payload-schemas/api.github.com/secret_scanning_alert/resolved.schema.json b/payload-schemas/api.github.com/secret_scanning_alert/resolved.schema.json
index 1f200dab2..731e65cf2 100644
--- a/payload-schemas/api.github.com/secret_scanning_alert/resolved.schema.json
+++ b/payload-schemas/api.github.com/secret_scanning_alert/resolved.schema.json
@@ -23,7 +23,7 @@
           "enum": ["false_positive", "wontfix", "revoked", "used_in_tests"]
         },
         "resolved_by": { "$ref": "common/user.schema.json" },
-        "resolved_at": { "type": "string" }
+        "resolved_at": { "type": "string", "format": "date-time" }
       },
       "additionalProperties": false
     },
diff --git a/payload-schemas/api.github.com/security_advisory/performed.schema.json b/payload-schemas/api.github.com/security_advisory/performed.schema.json
index 2f6ab65d1..52ca46dfa 100644
--- a/payload-schemas/api.github.com/security_advisory/performed.schema.json
+++ b/payload-schemas/api.github.com/security_advisory/performed.schema.json
@@ -69,9 +69,14 @@
             "additionalProperties": false
           }
         },
-        "published_at": { "type": "string" },
-        "updated_at": { "type": "string" },
-        "withdrawn_at": { "type": ["string", "null"] },
+        "published_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
+        "withdrawn_at": {
+          "oneOf": [
+            {"type": "null"},
+            {"type": "string", "format": "date-time"}
+          ]
+        },
         "vulnerabilities": {
           "type": "array",
           "items": {
diff --git a/payload-schemas/api.github.com/security_advisory/published.schema.json b/payload-schemas/api.github.com/security_advisory/published.schema.json
index 3752d0377..9a84c5d09 100644
--- a/payload-schemas/api.github.com/security_advisory/published.schema.json
+++ b/payload-schemas/api.github.com/security_advisory/published.schema.json
@@ -69,9 +69,14 @@
             "additionalProperties": false
           }
         },
-        "published_at": { "type": "string" },
-        "updated_at": { "type": "string" },
-        "withdrawn_at": { "type": ["string", "null"] },
+        "published_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
+        "withdrawn_at": {
+          "oneOf": [
+            {"type": "null"},
+            {"type": "string", "format": "date-time"}
+          ]
+        },
         "vulnerabilities": {
           "type": "array",
           "items": {
diff --git a/payload-schemas/api.github.com/security_advisory/updated.schema.json b/payload-schemas/api.github.com/security_advisory/updated.schema.json
index dfb0e6b23..4ddf149b5 100644
--- a/payload-schemas/api.github.com/security_advisory/updated.schema.json
+++ b/payload-schemas/api.github.com/security_advisory/updated.schema.json
@@ -69,9 +69,14 @@
             "additionalProperties": false
           }
         },
-        "published_at": { "type": "string" },
-        "updated_at": { "type": "string" },
-        "withdrawn_at": { "type": ["string", "null"] },
+        "published_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
+        "withdrawn_at": {
+          "oneOf": [
+            {"type": "null"},
+            {"type": "string", "format": "date-time"}
+          ]
+        },
         "vulnerabilities": {
           "type": "array",
           "items": {
diff --git a/payload-schemas/api.github.com/security_advisory/withdrawn.schema.json b/payload-schemas/api.github.com/security_advisory/withdrawn.schema.json
index 5cbafeb67..182fc6cea 100644
--- a/payload-schemas/api.github.com/security_advisory/withdrawn.schema.json
+++ b/payload-schemas/api.github.com/security_advisory/withdrawn.schema.json
@@ -69,9 +69,9 @@
             "additionalProperties": false
           }
         },
-        "published_at": { "type": "string" },
-        "updated_at": { "type": "string" },
-        "withdrawn_at": { "type": "string" },
+        "published_at": { "type": "string", "format": "date-time" },
+        "updated_at": { "type": "string", "format": "date-time" },
+        "withdrawn_at": { "type": "string", "format": "date-time" },
         "vulnerabilities": {
           "type": "array",
           "items": {
diff --git a/payload-schemas/api.github.com/sponsorship/cancelled.schema.json b/payload-schemas/api.github.com/sponsorship/cancelled.schema.json
index a9eb15292..f58c90bb3 100644
--- a/payload-schemas/api.github.com/sponsorship/cancelled.schema.json
+++ b/payload-schemas/api.github.com/sponsorship/cancelled.schema.json
@@ -17,7 +17,7 @@
       ],
       "properties": {
         "node_id": { "type": "string" },
-        "created_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
         "sponsorable": { "$ref": "common/user.schema.json" },
         "sponsor": { "$ref": "common/user.schema.json" },
         "privacy_level": { "type": "string" },
diff --git a/payload-schemas/api.github.com/sponsorship/created.schema.json b/payload-schemas/api.github.com/sponsorship/created.schema.json
index fb7e75f59..071ffe15a 100644
--- a/payload-schemas/api.github.com/sponsorship/created.schema.json
+++ b/payload-schemas/api.github.com/sponsorship/created.schema.json
@@ -17,7 +17,7 @@
       ],
       "properties": {
         "node_id": { "type": "string" },
-        "created_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
         "sponsorable": { "$ref": "common/user.schema.json" },
         "sponsor": { "$ref": "common/user.schema.json" },
         "privacy_level": { "type": "string" },
diff --git a/payload-schemas/api.github.com/sponsorship/edited.schema.json b/payload-schemas/api.github.com/sponsorship/edited.schema.json
index ae5f10ad9..4781d06a3 100644
--- a/payload-schemas/api.github.com/sponsorship/edited.schema.json
+++ b/payload-schemas/api.github.com/sponsorship/edited.schema.json
@@ -17,7 +17,7 @@
       ],
       "properties": {
         "node_id": { "type": "string" },
-        "created_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
         "sponsorable": { "$ref": "common/user.schema.json" },
         "sponsor": { "$ref": "common/user.schema.json" },
         "privacy_level": { "type": "string" },
diff --git a/payload-schemas/api.github.com/sponsorship/pending_cancellation.schema.json b/payload-schemas/api.github.com/sponsorship/pending_cancellation.schema.json
index b41a0c6c3..fee6c3ffe 100644
--- a/payload-schemas/api.github.com/sponsorship/pending_cancellation.schema.json
+++ b/payload-schemas/api.github.com/sponsorship/pending_cancellation.schema.json
@@ -17,7 +17,7 @@
       ],
       "properties": {
         "node_id": { "type": "string" },
-        "created_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
         "sponsorable": { "$ref": "common/user.schema.json" },
         "sponsor": { "$ref": "common/user.schema.json" },
         "privacy_level": { "type": "string" },
diff --git a/payload-schemas/api.github.com/sponsorship/pending_tier_change.schema.json b/payload-schemas/api.github.com/sponsorship/pending_tier_change.schema.json
index 16c16801a..27c468cfe 100644
--- a/payload-schemas/api.github.com/sponsorship/pending_tier_change.schema.json
+++ b/payload-schemas/api.github.com/sponsorship/pending_tier_change.schema.json
@@ -17,7 +17,7 @@
       ],
       "properties": {
         "node_id": { "type": "string" },
-        "created_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
         "sponsorable": { "$ref": "common/user.schema.json" },
         "sponsor": { "$ref": "common/user.schema.json" },
         "privacy_level": { "type": "string" },
diff --git a/payload-schemas/api.github.com/sponsorship/tier_changed.schema.json b/payload-schemas/api.github.com/sponsorship/tier_changed.schema.json
index c29fb6880..032e2b365 100644
--- a/payload-schemas/api.github.com/sponsorship/tier_changed.schema.json
+++ b/payload-schemas/api.github.com/sponsorship/tier_changed.schema.json
@@ -17,7 +17,7 @@
       ],
       "properties": {
         "node_id": { "type": "string" },
-        "created_at": { "type": "string" },
+        "created_at": { "type": "string", "format": "date-time" },
         "sponsorable": { "$ref": "common/user.schema.json" },
         "sponsor": { "$ref": "common/user.schema.json" },
         "privacy_level": { "type": "string" },
diff --git a/payload-schemas/api.github.com/star/created.schema.json b/payload-schemas/api.github.com/star/created.schema.json
index 90ec49783..8d64079b6 100644
--- a/payload-schemas/api.github.com/star/created.schema.json
+++ b/payload-schemas/api.github.com/star/created.schema.json
@@ -7,6 +7,7 @@
     "action": { "type": "string", "enum": ["created"] },
     "starred_at": {
       "type": "string",
+      "format": "date-time",
       "description": "The time the star was created. This is a timestamp in ISO 8601 format: `YYYY-MM-DDTHH:MM:SSZ`. Will be `null` for the `deleted` action."
     },
     "repository": { "$ref": "common/repository.schema.json" },
diff --git a/payload-schemas/api.github.com/status/event.schema.json b/payload-schemas/api.github.com/status/event.schema.json
index 1580c6253..d34f0be41 100644
--- a/payload-schemas/api.github.com/status/event.schema.json
+++ b/payload-schemas/api.github.com/status/event.schema.json
@@ -179,8 +179,8 @@
         "additionalProperties": false
       }
     },
-    "created_at": { "type": "string" },
-    "updated_at": { "type": "string" },
+    "created_at": { "type": "string", "format": "date-time" },
+    "updated_at": { "type": "string", "format": "date-time" },
     "repository": { "$ref": "common/repository.schema.json" },
     "sender": { "$ref": "common/user.schema.json" },
     "installation": { "$ref": "common/installation-lite.schema.json" },
diff --git a/payload-types/schema.d.ts b/payload-types/schema.d.ts
index 3149dc19f..f4b9b52eb 100644
--- a/payload-types/schema.d.ts
+++ b/payload-types/schema.d.ts
@@ -978,7 +978,7 @@ export interface CheckRunCreatedEvent {
     /**
      * The time the check completed. This is a timestamp in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format: `YYYY-MM-DDTHH:MM:SSZ`.
      */
-    completed_at: string | null;
+    completed_at: null | string;
     output: {
       title?: string | null;
       summary: string | null;
@@ -1089,7 +1089,7 @@ export interface CheckRunRequestedActionEvent {
     /**
      * The time the check completed. This is a timestamp in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format: `YYYY-MM-DDTHH:MM:SSZ`.
      */
-    completed_at: string | null;
+    completed_at: null | string;
     output: {
       title?: string | null;
       summary: string | null;
@@ -2310,7 +2310,7 @@ export interface Discussion {
     is_answerable: boolean;
   };
   answer_html_url: string | null;
-  answer_chosen_at: string | null;
+  answer_chosen_at: null | string;
   answer_chosen_by: User | null;
   html_url: string;
   id: number;
@@ -4810,8 +4810,8 @@ export interface SimplePullRequest {
   body: string;
   created_at: string;
   updated_at: string;
-  closed_at: string | null;
-  merged_at: string | null;
+  closed_at: null | string;
+  merged_at: null | string;
   merge_commit_sha: string | null;
   assignee: User | null;
   assignees: User[];
@@ -4952,8 +4952,8 @@ export interface PullRequestReviewCommentCreatedEvent {
     body: string;
     created_at: string;
     updated_at: string;
-    closed_at: string | null;
-    merged_at: string | null;
+    closed_at: null | string;
+    merged_at: null | string;
     merge_commit_sha: string | null;
     assignee: User | null;
     assignees: User[];
@@ -5114,8 +5114,8 @@ export interface PullRequestReviewCommentDeletedEvent {
     body: string;
     created_at: string;
     updated_at: string;
-    closed_at: string | null;
-    merged_at: string | null;
+    closed_at: null | string;
+    merged_at: null | string;
     merge_commit_sha: string | null;
     assignee: User | null;
     assignees: User[];
@@ -5192,8 +5192,8 @@ export interface PullRequestReviewCommentEditedEvent {
     body: string;
     created_at: string;
     updated_at: string;
-    closed_at: string | null;
-    merged_at: string | null;
+    closed_at: null | string;
+    merged_at: null | string;
     merge_commit_sha: string | null;
     assignee: User | null;
     assignees: User[];
@@ -5749,7 +5749,7 @@ export interface SecurityAdvisoryPerformedEvent {
     }[];
     published_at: string;
     updated_at: string;
-    withdrawn_at: string | null;
+    withdrawn_at: null | string;
     vulnerabilities: {
       package: {
         ecosystem: string;
@@ -5790,7 +5790,7 @@ export interface SecurityAdvisoryPublishedEvent {
     }[];
     published_at: string;
     updated_at: string;
-    withdrawn_at: string | null;
+    withdrawn_at: null | string;
     vulnerabilities: {
       package: {
         ecosystem: string;
@@ -5831,7 +5831,7 @@ export interface SecurityAdvisoryUpdatedEvent {
     }[];
     published_at: string;
     updated_at: string;
-    withdrawn_at: string | null;
+    withdrawn_at: null | string;
     vulnerabilities: {
       package: {
         ecosystem: string;
@@ -6275,7 +6275,7 @@ export interface WorkflowJob {
    */
   runner_group_name: string | null;
   started_at: string;
-  completed_at: string | null;
+  completed_at: null | string;
 }
 export interface WorkflowStepInProgress {
   name: string;