OpenAI uses a simple versioning scheme via the openai-version response header. The current version is 2020-10-01 — a surprisingly old date that reflects their commitment to backwards compatibility.
How Versioning Works
- The
openai-versionheader is returned in every response. - OpenAI maintains backwards compatibility for existing endpoints.
- New features are added additively (new parameters, new response fields).
- Deprecated features follow a published deprecation schedule with advance notice.
Response Headers for Debugging
| Header | Description |
|---|---|
openai-organization | Organization associated with the request |
openai-processing-ms | Server-side processing time |
openai-version | REST API version (currently 2020-10-01) |
x-request-id | Unique request ID for support tickets |
Deprecation Policy
Models are deprecated with advance notice. For example, the Assistants API was deprecated August 26, 2026, with migration guidance to the Responses API. Old model versions (like gpt-4-turbo) remain available but may have higher pricing. Always test against new model versions before switching production workloads.