API Reference
API Reference
Every public LettrLabs API operation, grouped by area, with an interactive request console.
The reference below is generated from the LettrLabs public OpenAPI schema, so
it always matches the live API. Every operation lists its parameters, request and
response schemas, status codes, and the X-API-KEY authentication requirement —
and each page has an interactive “try it” console you can call with your own
key.
Groups
- Profile — your account profile (
GET /v1/me). - Orders — create, inspect, and manage direct‑mail orders, recipients, proofs, and checkout.
- Conversions — record and read back conversions for attribution.
- Automations — integration‑driven order endpoints.
- Order Recipient Analytics — recipient‑level statistics for an order.
- Address Book — add address‑book entries.
Before you call
Generate a key (see Authentication & API keys)
and send it in the X-API-KEY header. All requests use the base URL
https://app.lettrlabs.com/api.
Building with an AI agent?
Point your agent at /llms.txt for a curated index of these pages,
or /llms-full.txt for the entire reference and guides as a
single file — so it can build against the LettrLabs API effectively.