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 to run Codex -> GoModel -> ChatGPT subscription.

Configure

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

CHATGPT_API_KEY=$(jq -r .tokens.access_token ~/.codex/auth.json)

Or in config.yaml:

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.

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.

Models

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

gpt-5.6-sol, gpt-5.6-terra, gpt-5.6-luna, gpt-5.5

Override it when your plan serves a different set:

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 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, budgets, and cost load balancing.

A budget can therefore reject chatgpt traffic for “spending” money the subscription never charges. Scope budgets to a user path that excludes subscription traffic, or leave budgets off for it. Declaring per-model pricing and modes: ["responses"] in 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.

Limits

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

{"error":{"message":"The usage limit has been reached","type":"rate_limit_error"}}

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.