> ## Documentation Index
> Fetch the complete documentation index at: https://gomodel-refactor-aliases.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# ChatGPT subscription

> Route Responses API traffic through a ChatGPT subscription instead of an OpenAI Platform API key.

The `chatgpt` provider calls the Codex backend that ships with a ChatGPT
subscription (Plus, Pro, Business, or Enterprise). Usage is billed against the
subscription's quota, not an OpenAI Platform API key.

Pair it with the [Codex guide](/guides/codex) to run
`Codex -> GoModel -> ChatGPT subscription`.

## Configure

The credential is the access token from your Codex sign-in:

```bash theme={null}
CHATGPT_API_KEY=$(jq -r .tokens.access_token ~/.codex/auth.json)
```

Or in `config.yaml`:

```yaml theme={null}
providers:
  chatgpt:
    type: chatgpt
    api_key: "${CHATGPT_API_KEY}"
```

Run `codex login` first if `~/.codex/auth.json` does not exist yet. GoModel
derives the ChatGPT account ID from the token itself, so nothing else is
needed.

<Warning>
  The token expires roughly every 10 days. Re-export it (the Codex CLI
  refreshes the file whenever it runs) or run `codex login` again when requests
  start returning 401.
</Warning>

## Models

The Codex backend has no model-listing endpoint, so GoModel ships the
inventory a ChatGPT subscription can call:

```text theme={null}
gpt-5.6-sol, gpt-5.6-terra, gpt-5.6-luna, gpt-5.5
```

Override it when your plan serves a different set:

```bash theme={null}
CHATGPT_MODELS=gpt-5.6-sol,gpt-5.6-terra
```

A model outside the plan's set is rejected upstream with `The '<model>' model
is not supported when using Codex with a ChatGPT account`.

`gpt-5.4` and `gpt-5.4-mini` leave ChatGPT-authenticated Codex on August 31,
2026; use `gpt-5.6-terra` and `gpt-5.6-luna` instead. Both stay available to
Codex sessions authenticated with an OpenAI API key, through the `openai`
provider.

## Responses API only

The Codex backend serves `/responses` and nothing else, so
`/v1/chat/completions` and `/v1/embeddings` answer `501` for `chatgpt` models.
Use `/v1/responses`, which is what Codex sends anyway.

The backend also validates against a strict parameter allowlist. GoModel
adapts requests rather than failing them, so callers keep using the standard
Responses API:

| Request field                                                                                                                         | Behavior                                                       |
| ------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------- |
| `stream`, `store`                                                                                                                     | Pinned to `true` / `false` — the backend rejects anything else |
| `input` as a string                                                                                                                   | Wrapped into the message list the backend requires             |
| `instructions`, `tools`, `tool_choice`, `parallel_tool_calls`, `reasoning`, `text`, `include`                                         | Forwarded                                                      |
| `temperature`, `top_p`, `max_output_tokens`, `previous_response_id`, `truncation`, `metadata`, `user`, `service_tier`, `top_logprobs` | Dropped — unsupported upstream                                 |

Because the backend streams only, a non-streaming `POST /v1/responses` is
served by streaming upstream and returning the final response object. Clients
see a normal non-streaming response. See
[Responses compatibility](/advanced/responses-compatibility) for how the
gateway's Responses surface behaves across providers.

## Reported cost is not real spend

Subscription usage is flat-rate, but these model IDs also exist on the OpenAI
Platform, so the model catalog attaches their per-token API prices. Usage
records and dashboard totals for `chatgpt` show a figure that corresponds to no
actual charge, and the same collision makes `GET /v1/models` advertise
`modes: ["chat", "responses"]`.

The modes are cosmetic — they drive dashboard grouping, not routing. Pricing is
not: it feeds [cost tracking](/features/cost-tracking), budgets, and `cost`
load balancing.

<Warning>
  A **budget** can therefore reject `chatgpt` traffic for "spending" money the
  subscription never charges. Scope budgets to a
  [user path](/features/user-path) that excludes subscription traffic, or leave
  budgets off for it. Declaring per-model `pricing` and `modes: ["responses"]`
  in [model metadata](/advanced/model-metadata) corrects what `/v1/models`
  advertises, but usage records still price at catalog rates. Declare every
  model you want served: the list replaces the default inventory rather than
  adding to it.
</Warning>

## Limits

Subscription quota is separate from API credit. When it is exhausted the
gateway relays a `429`:

```json theme={null}
{"error":{"message":"The usage limit has been reached","type":"rate_limit_error"}}
```

<Warning>
  OpenAI authorizes these tokens for Codex traffic. Use this provider to route
  your own Codex usage through GoModel, not as a general-purpose inference API.
</Warning>