ChatGPT Subscription

Use ChatGPT Pro/Max subscription models through LiteLLM with OAuth device flow authentication.

ChatGPT subscription access is native to the Responses API. Chat Completions requests are bridged to Responses for supported models (for example chatgpt/gpt-5.4).

Notes:

• The ChatGPT subscription backend rejects token limit fields (max_tokens, max_output_tokens, max_completion_tokens) and metadata. LiteLLM strips these fields for this provider.
• /v1/chat/completions honors stream. When stream is false (default), LiteLLM aggregates the Responses stream into a single JSON response.

Authentication

ChatGPT subscription access uses an OAuth device code flow:

1. LiteLLM prints a device code and verification URL
2. Open the URL, sign in, and enter the code
3. Tokens are stored locally for reuse

Usage - LiteLLM Python SDK

Responses (recommended for Codex models)

response = litellm.responses(
    model="chatgpt/gpt-5.3-codex",
    input="Write a Python hello world"
)

print(response)

Chat Completions (bridged to Responses)

response = litellm.completion(
    model="chatgpt/gpt-5.4",
    messages=[{"role": "user", "content": "Write a Python hello world"}]
)

print(response)

Usage - LiteLLM Proxy

model_list:
  - model_name: chatgpt/gpt-5.4
    model_info:
      mode: responses
    litellm_params:
      model: chatgpt/gpt-5.4
  - model_name: chatgpt/gpt-5.4-pro
    model_info:
      mode: responses
    litellm_params:
      model: chatgpt/gpt-5.4-pro
  - model_name: chatgpt/gpt-5.3-codex
    model_info:
      mode: responses
    litellm_params:
      model: chatgpt/gpt-5.3-codex
  - model_name: chatgpt/gpt-5.3-codex-spark
    model_info:
      mode: responses
    litellm_params:
      model: chatgpt/gpt-5.3-codex-spark
  - model_name: chatgpt/gpt-5.3-instant
    model_info:
      mode: responses
    litellm_params:
      model: chatgpt/gpt-5.3-instant
  - model_name: chatgpt/gpt-5.3-chat-latest
    model_info:
      mode: responses
    litellm_params:
      model: chatgpt/gpt-5.3-chat-latest

litellm --config config.yaml

Configuration

Environment Variables

• CHATGPT_TOKEN_DIR: Custom token storage directory
• CHATGPT_AUTH_FILE: Auth file name (default: auth.json)
• CHATGPT_API_BASE: Override API base (default: https://chatgpt.com/backend-api/codex)
• OPENAI_CHATGPT_API_BASE: Alias for CHATGPT_API_BASE
• CHATGPT_ORIGINATOR: Override the originator header value
• CHATGPT_USER_AGENT: Override the User-Agent header value
• CHATGPT_USER_AGENT_SUFFIX: Optional suffix appended to the User-Agent header