Authentication & API keys
Generate a public API key in the LettrLabs app and authenticate requests with the X-API-KEY header.
The LettrLabs public API authenticates every request with a public API key
sent in the X-API-KEY header. You generate the key once, inside the
LettrLabs app, and use it for all subsequent calls.
Generate an API key
In the LettrLabs app:
- Open Automations.
- Go to Setup.
- Select OpenAPI.
- Click Manage.
- Click Generate Key.
Your new key is shown once, at creation time — copy it immediately and store it somewhere secure (a secret manager or your server's environment). If you lose it, generate a new key and update your integration.
Treat the key like a password. It grants full access to your account's public API surface. Never embed it in client‑side code, a mobile app, or a public repository — keep it server‑side.
Authenticate a request
Send the key in the X-API-KEY header on every request:
curl https://app.lettrlabs.com/api/v1/me \
-H "X-API-KEY: your_api_key_here"A quick way to confirm a key works is GET /v1/me, which returns your profile.
A missing or invalid X-API-KEY header returns 401 Unauthorized.
GET /v1/me HTTP/1.1
Host: app.lettrlabs.com
X-API-KEY: your_api_key_hereEvery endpoint in the API Reference shows the same
X-API-KEY requirement, and the interactive console lets you paste your key and
call the endpoint live.
Rotating keys
To rotate, generate a new key (same steps above), deploy it to your integration, then stop using the old one. Generating a key does not automatically revoke previous keys.