GPTKit

GPTKit is a unified backend designed to provide tools via HTTP Actions for Custom GPTs.

Authentication

All endpoints require Bearer token authentication. The GPTKIT_BEARER_TOKEN environment variable must be set for the API to function (unless disabled in development mode).

Usage

When calling the API, include the Bearer token in the Authorization header:

curl -H "Authorization: Bearer your-token-here" \
  "https://gptkit.guillaumeduveau.com/domain/availability?domain=example.com"

Configuration

Production (Docker)

Use a .env file with Docker Compose (see Deployment section):

# .env
GPTKIT_BEARER_TOKEN=your-secret-token-here

Local Development

GPTKit now targets Python 3.14+ and uses uv for all local commands.

For local development, you can disable authentication:

export GPTKIT_DISABLE_AUTH=1
uv run uvicorn app.main:app --reload

Or set the token normally:

export GPTKIT_BEARER_TOKEN="your-secret-token-here"
uv run uvicorn app.main:app --reload

Tools

Domain Availability (/domain/availability)

Checks whether a single domain is available, with a response shape optimized for Custom GPT Actions.

• Endpoint: GET /domain/availability
• Parameters:
  • domain (required): Full domain name including TLD, for example example.com or monsite.fr.
  • refresh (optional): 1 to bypass the cache and force a fresh WHOIS lookup.
• Features:
  • Persistent cache (SQLite).
  • Rate limiting (global and per domain).
  • Internal WHOIS collection kept for caching, without exposing WHOIS details in the public response.
  • Stable single-domain response for GPT Actions.

Example response:

{
  "domain": "example.com",
  "available": true,
  "checked_at": "2026-04-24T12:34:56Z",
  "status": "ok"
}

Deployment

Docker Compose

Here is an example docker-compose.yml configuration to deploy GPTKit.

Note: The image is available on GHCR. Make sure to replace your-username with your GitHub username.

services:
  gptkit:
    image: ghcr.io/your-username/gptkit:latest
    restart: unless-stopped
    ports:
      - "8000:8000"
    environment:
      - GPTKIT_BEARER_TOKEN=${GPTKIT_BEARER_TOKEN}
    volumes:
      # Data persistence (WHOIS cache stored in /app/data/whois_cache.db)
      - gptkit_data:/app/data

volumes:
  gptkit_data:

Create a .env file in the same directory as docker-compose.yml (see .env.example for reference):

# .env (do not commit this file!)
GPTKIT_BEARER_TOKEN=your-secret-token-here

Docker Compose will automatically load variables from the .env file or from the host environment.

Security: Never commit the .env file to version control. It's already in .gitignore. Copy .env.example to .env and set your values.

Development

1. Installation:

   uv sync --dev

2. Run:

   uv run uvicorn app.main:app --reload

3. Tests:

• Quick API smoke test (curl):

  # Without authentication (if GPTKIT_BEARER_TOKEN is not set)
  curl "http://localhost:8000/domain/availability?domain=example.com"
  
  # With authentication
  curl -H "Authorization: Bearer your-token-here" \
    "http://localhost:8000/domain/availability?domain=example.fr&refresh=1"

• Run the unit test suite with pytest (from the project root):

  # sync the project environment
  uv sync --dev
  
  # run all tests
  uv run pytest -q
  
  # run a single test file
  uv run pytest tests/test_whois_parsing.py -q