Model retirements · OpenAI API · checked

gpt-5.3-codex shutdown on 1 April 2027

OpenAI shuts down gpt-5.3-codex on the OpenAI API on 1 April 2027 and recommends gpt-6-sol as the replacement. At list prices gpt-6-sol costs 1.1× gpt-5.3-codex's input price and 0.71× its output price per token. OpenAI's deprecation page documents no API changes for this move. Record your answers before 1 April 2027: after that nobody can ask gpt-5.3-codex again.

Find every place your code and config name it, with this page's facts beside each:

$ npx --allow-git=root github:agentwares/model-migrate scan

npx --allow-git=root github:agentwares/model-migrate scan lists every model ID in your code and config that has a shutdown date, with its replacement, price ratio and this page's link. It needs no account and no API key, reads your files on your machine and sends nothing; its one request fetches this data. Free and MIT licensed.

The facts

Platform
OpenAI API
Model ID
gpt-5.3-codex
Announced
1 October 2026
Shutdown
1 April 2027
Recommended replacement
gpt-6-sol
List price per million tokens, input / output

gpt-6-sol: $2 / $10 against $1.75 / $14, so 1.1× input, 0.71× output

Prices are the provider's list prices for the standard tier, text input and the shortest context tier, read on 8 October 2026. A per-token ratio leaves out how many tokens each model spends on the same prompt; only your own prompts show that.

What changes when you move

OpenAI's deprecation page lists no parameter or API changes for this move. The model's answers still change: a replacement is a different model.

How to test the replacement on your own prompts

  1. Find every call that names gpt-5.3-codex: npx --allow-git=root github:agentwares/model-migrate scan prints each file and line.
  2. Before 1 April 2027, record what gpt-5.3-codex answers on a sample of your real prompts, with the token counts OpenAI reports, on your own key: npx --allow-git=root github:agentwares/model-migrate capture prompts.jsonl --model gpt-5.3-codex. After the shutdown that record cannot be made.
  3. Run the same prompts on gpt-6-sol, a cheaper sibling and a model from another provider, and compare with checks that need no judge: exact or normalised match, JSON validity and schema, tool-call names and arguments, refusals and length. npx --allow-git=root github:agentwares/model-migrate compare does this on your keys.
  4. Price the move with the token counts each provider reports for those prompts, not with the list price alone; compare reports the cost per 1,000 calls.

Keep testing until the date

capture and compare run on your keys and keep everything on your machine. To re-run the same prompts against your own endpoint whenever a provider ships a model, with the history kept, npx --allow-git=root github:agentwares/model-migrate export --agentcheck writes them as traces that agentcheck imports onto a target you monitor there. On its Pro plan they become checks that re-run when a provider ships a model, with 90 days of history.

Migration watch is not built. It would re-run your captured prompts on each replacement and each new model until 1 April 2027, with no endpoint needed, and email you what changed. If you would pay for that, say so with one click. The click is counted; nothing else is sent or stored.

Also shutting down on 1 April 2027

Other OpenAI API retirements

Every announced shutdown, by date

Sources

Built only from the providers' own pages. No vendor intent is implied: a date is what the page says on the day it was read. Data: /models/retirements.json.

model-migrate is a free tool from agentcheck, which re-runs an agent's checks when a provider ships a model and replays recorded traces nightly, so a model change that breaks it arrives as one diff by email.