FastApps

The python framework for apps in ChatGPT

📚 Documentation: https://docs.fastapps.org/

👥 Community: Join Our Discord

Quick Start

We recommend installing FastApps with uv:

uv tool install fastapps
uv tool install --upgrade fastapps # Update to the latest version

For full installation instructions, including verification, upgrading from the official MCPSDK, and developer setup, see the Installation Guide.

Then, you can quickstart by running commands below :

uv run fastapps init my-app
cd my-app
uv sync          # Install Python deps & create uv.lock
uv run fastapps dev

That's it! You'll gonna see an image with a public url. You can test the server with following guides.

The public url is one-time, generated with cloudflare tunnel.

Managing Dependencies with uv

FastApps projects now rely on pyproject.toml + uv.lock for Python dependencies.

• uv sync installs everything defined in pyproject.toml and writes/updates uv.lock for reproducible builds. Run it whenever you pull new changes or after editing dependencies.
• uv add <package> adds new dependencies and immediately updates both pyproject.toml and uv.lock.
• uv run <command> executes CLI tools (like fastapps dev) inside the synced environment without activating a virtualenv manually.

Tip: If uv is not installed, follow their installation instructions and rerun uv sync. Without uv, FastApps commands that manage dependencies (e.g., fastapps init, fastapps use) will fail with a helpful error message.

Test App

MCP server is available at /mcp endpoint of fastapps server.
Example : https://your-public-url.trycloudflare.com/mcp

Option A: Test on MCPJam Inspector

Add your public URL + /mcp to ChatGPT.

npx @mcpjam/inspector@latest

Option B: Test on ChatGPT

Add your public URL + /mcp to ChatGPT's "Settings > Connectors" .

Creating More Widgets

uv run fastapps create additional-widget

Using Widget Templates

FastApps provides pre-built templates to jumpstart your widget development:

# Create widget from a template
uv run fastapps create my-list --template list          # Vertical list with items
uv run fastapps create my-carousel --template carousel  # Horizontal scrolling cards
uv run fastapps create my-albums --template albums      # Photo gallery viewer

Editing Your Widget

You'll only need to edit these 2 folders:

server/tools/

This folder contains backend .py files, where you define conditions & server logics for the app.

Example :

### my_widget_tool.py
from fastapps import BaseWidget, Field, ConfigDict
from pydantic import BaseModel
from typing import Dict, Any

class MyWidgetInput(BaseModel):
    model_config = ConfigDict(populate_by_name=True)
    name: str = Field(default="World")

class MyWidgetTool(BaseWidget):
    identifier = "my-widget"
    title = "My Widget"
    input_schema = MyWidgetInput
    invoking = "Processing..."
    invoked = "Done!"
    
    widget_csp = {
        "connect_domains": [],      # APIs you'll call
        "resource_domains": []      # Images/fonts you'll use
    }
    
    async def execute(self, input_data: MyWidgetInput) -> Dict[str, Any]:
        # Your logic here
        return {
            "name": input_data.name,
            "message": f"Hello, {input_data.name}!"
        }

widgets/ - Frontend UI

The folder contains frontend component codes that will show up on the app screen according to the rules you've define with python codes above.

Apps in GPT components are react components - FastApps follows it. You can custom compoenents as you wish.

// my-widget/index.jsx
import React from 'react';
import { useWidgetProps } from 'fastapps';

export default function MyWidget() {
  const props = useWidgetProps();
  
  return (
    <div style={{
      padding: '40px',
      textAlign: 'center',
      background: '#4A90E2',
      color: 'white',
      borderRadius: '12px'
    }}>
      <h1>{props.message}</h1>
      <p>Welcome, {props.name}!</p>
    </div>
  );
}

That's it! These are the only files you need to write.

Contributing

We welcome contributions! Please see our contributing guidelines:

• Contributing Guide - How to contribute to FastApps
• Code Style Guide - Code formatting and style standards
• GitHub Workflows - CI/CD documentation

Quick Start for Contributors

# Fork and clone the repository
git clone https://github.com/YOUR_USERNAME/FastApps.git
cd FastApps

# Install uv (if not already installed)
# curl -LsSf https://astral.sh/uv/install.sh | sh

# Install development dependencies (recommended - matches CI)
uv sync --dev

# Install pre-commit hooks (already installed via uv sync --dev)
uv run pre-commit install

# Make changes and ensure they pass checks
uv run black .
uv run ruff check --fix .
uv run pytest

# Submit a pull request

License

MIT © Dooi Labs

Links

• PyPI: https://pypi.org/project/fastapps/
• React Hooks: https://www.npmjs.com/package/fastapps
• GitHub: https://github.com/DooiLabs/FastApps
• MCP Spec: https://modelcontextprotocol.io/