# ChatMock
**Allows Codex to work in your favourite chat apps and coding tools.**
[](https://pypi.org/project/chatmock/)
[](https://pypi.org/project/chatmock/)
[](LICENSE)
[](https://github.com/RayBytes/ChatMock/stargazers)
[](https://github.com/RayBytes/ChatMock/commits/main)
[](https://github.com/RayBytes/ChatMock/issues)
## Install
#### Homebrew
```bash
brew tap RayBytes/chatmock
brew install chatmock
```
#### pipx / pip
```bash
pipx install chatmock
```
#### GUI
Download from [releases](https://github.com/RayBytes/ChatMock/releases) (macOS & Windows)
#### Docker
See [DOCKER.md](DOCKER.md)
## Getting Started
```bash
# 1. Sign in with your ChatGPT account
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.
## Usage
Python
```python
from openai import OpenAI
client = OpenAI(
base_url="http://127.0.0.1:8000/v1",
api_key="anything" # not checked
)
response = client.chat.completions.create(
model="gpt-5.4",
messages=[{"role": "user", "content": "hello"}]
)
print(response.choices[0].message.content)
```
cURL
```bash
curl http://127.0.0.1:8000/v1/chat/completions \
-H "Content-Type: application/json" \
-d '{
"model": "gpt-5.4",
"messages": [{"role": "user", "content": "hello"}]
}'
```
## Supported Models
- `gpt-5.5`
- `gpt-5.5-pro` (preset for `gpt-5.5` with xhigh reasoning)
- `gpt-5.4`
- `gpt-5.4-mini`
- `gpt-5.2`
- `gpt-5.1`
- `gpt-5`
- `gpt-5.3-codex`
- `gpt-5.3-codex-spark`
- `gpt-5.2-codex`
- `gpt-5-codex`
- `gpt-5.1-codex`
- `gpt-5.1-codex-max`
- `gpt-5.1-codex-mini`
- `codex-mini`
## 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.
| Flag | Env var | Options | Default | Description |
|------|---------|---------|---------|-------------|
| `--reasoning-effort` | `CHATGPT_LOCAL_REASONING_EFFORT` | none, minimal, low, medium, high, xhigh | medium | How hard the model thinks |
| `--reasoning-summary` | `CHATGPT_LOCAL_REASONING_SUMMARY` | auto, concise, detailed, none | auto | Thinking summary verbosity |
| `--reasoning-compat` | `CHATGPT_LOCAL_REASONING_COMPAT` | legacy, o3, think-tags | think-tags | How reasoning is returned to the client |
| `--fast-mode` | `CHATGPT_LOCAL_FAST_MODE` | true/false | false | Priority processing for supported models |
| `--enable-web-search` | `CHATGPT_LOCAL_ENABLE_WEB_SEARCH` | true/false | false | Allow the model to search the web |
| `--expose-reasoning-models` | `CHATGPT_LOCAL_EXPOSE_REASONING_MODELS` | true/false | false | List each reasoning level as its own model |
Web search in a request
```json
{
"model": "gpt-5.4",
"messages": [{"role": "user", "content": "latest news on ..."}],
"responses_tools": [{"type": "web_search"}],
"responses_tool_choice": "auto"
}
```
Fast mode in a request
```json
{
"model": "gpt-5.4",
"input": "summarize this",
"fast_mode": true
}
```
## Notes
Use responsibly and at your own risk. This project is not affiliated with OpenAI.
## Star History
[](https://www.star-history.com/#RayBytes/ChatMock&Timeline)