GPT-5.3 Codex, GPT-5.1 and GPT-5.4 Nano retire from the API April 1, 2027
OpenAI schedules API removal of gpt-5.3-codex, gpt-5.1 and gpt-5.4-nano for April 1, 2027. Its table recommends GPT-6 Sol for Codex and GPT-5.1, and GPT-6 Luna for Nano.
Required action
Inventory the three exact IDs in deployed configuration. Test the mapped replacement on the supported API surface before April 1; review request fields, tool routing, outputs, latency and cost.
Exact IDs and replacements
| Retiring API ID | Documented replacement | Shutdown date |
|---|---|---|
| gpt-5.3-codex | gpt-6-sol | 2027-04-01 |
| gpt-5.1 | gpt-6-sol | 2027-04-01 |
| gpt-5.4-nano | gpt-6-luna | 2027-04-01 |
What the notice covers
The October 1 notice lists three exact API model IDs and an April 1, 2027 shutdown date. It does not announce the retirement of every GPT-5 model, every Codex snapshot, or a ChatGPT subscription feature.
Test each mapped replacement
Keep the three mappings separate. The GPT-6 Sol and Luna model cards recommend Responses for built-in tools and function calling. Chat Completions supports function calling only when reasoning_effort is none. For a tool-using application, review its API route as well as its model name. Validate request fields, output parsing and representative tasks before switching.
What has not been established
Kingy has not called these models, checked an account entitlement or reproduced a migration. The documented replacement does not prove equal output, price, latency or regional access. This candidate does not require a pricing claim to explain the deadline.
Evidence limits
Historical first-detection date is unverified. This packet was prepared from retained and newly retrieved official evidence; preparation and retrieval dates are not substituted for first detection.
- Exact IDs only; unrelated snapshots, aliases, ChatGPT and partner-serving schedules are excluded.
- No model availability, runtime retirement, account entitlement or migration was tested.
- Supported endpoint and tool-routing guidance is specific to the documented Sol and Luna targets.
- No price or output-equivalence claim is made.