Authentication

API Key Format

API keys use the format u2l_live_ followed by 32 random hexadecimal characters. The u2l_live_ prefix makes keys easy to identify and scan for accidental leaks.

Getting Your API Key

1. Log in to your U2L Dashboard
2. Navigate to Settings → API
3. Click Create API Key and optionally add a label (e.g., "Production", "CI/CD")
4. Copy the key immediately — it will only be shown once

Making Authenticated Requests

Include your API key in the Authorization header of every request using the Bearer scheme:

curl https://u2l.ai/api/v1/links \
  -H "Authorization: Bearer u2l_live_your_api_key"

Error Responses

If authentication fails, the API returns a 401 or 403 status code:

Missing or invalid key

{
  "error": {
    "code": "unauthorized",
    "message": "Missing API key. Include it as: Authorization: Bearer u2l_live_..."
  }
}

Invalid format

{
  "error": {
    "code": "unauthorized",
    "message": "Invalid API key format. Keys start with u2l_live_ followed by 32 characters."
  }
}

Free plan user

{
  "error": {
    "code": "forbidden",
    "message": "API access requires Pro plan or above."
  }
}

API Key Limits by Plan