Install

Homebrew

brew tap RayBytes/chatmock
brew install chatmock

pipx / pip

pipx install chatmock

GUI

Download from releases (macOS & Windows)

Docker

See DOCKER.md

Getting Started

# 1. Sign in with your ChatGPT account
# If you are running this on a headless server, append --headless
chatmock login

# 2. Start the server
chatmock serve

The server runs at http://127.0.0.1:8000 by default. Use http://127.0.0.1:8000/v1 as your base URL for OpenAI-compatible apps.

Example usage

Supported Models

ChatMock automatically discovers the models available to the signed-in ChatGPT account. The current catalog commonly includes:

• gpt-5.6-sol
• gpt-5.6-terra
• gpt-5.6-luna
• gpt-5.5
• gpt-5.4
• gpt-5.4-mini
• gpt-5.3-codex-spark

Features

• Tool / function calling
• Vision / image input
• Thinking summaries (via think tags)
• Configurable thinking effort
• Fast mode for supported models
• Web search tool
• OpenAI-compatible /v1/responses (HTTP + WebSocket)
• Ollama-compatible endpoints
• Reasoning effort exposed as separate models (optional)

Configuration

All flags go after chatmock serve. These can also be set as environment variables.

{
  "model": "gpt-5.4",
  "messages": [{"role": "user", "content": "latest news on ..."}],
  "responses_tools": [{"type": "web_search"}],
  "responses_tool_choice": "auto"
}

{
  "model": "gpt-5.4",
  "input": "summarize this",
  "fast_mode": true
}

Important notice

Use responsibly and at your own risk. This project is not affiliated with OpenAI.

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