# Introduction (/)



The LettrLabs API lets you drive real, physical direct mail from your own
systems: create orders from a template, target recipients, track delivery and
conversions, and receive events as they happen. Everything the LettrLabs app
does for direct‑mail automation is available over a simple HTTPS + JSON API.

<Callout>
  **Building with an AI agent?** Point it at [`/llms.txt`](/llms.txt) for a
  curated index of these docs, or [`/llms-full.txt`](/llms-full.txt) for the
  full content as a single file — so it can build against the LettrLabs API
  effectively.
</Callout>

## What you can do [#what-you-can-do]

* **Create orders** from a template and a recipient list — handwritten cards and
  printed mail, sent on your schedule (see [Creating an Order](/creating-an-order)).
* **Attribute and convert** — record conversions against the mail you send and
  read them back for reporting (see [Attributions & Conversions](/attributions-and-conversions)).
* **Manage your address book and recipients** — add entries and adjust an order's
  recipients before it mails.
* **React to events** — receive inbound webhooks when something happens, with
  optional HMAC signature verification (see [Inbound webhooks](/inbound-webhooks)).

## Base URL [#base-url]

All requests go to:

```
https://app.lettrlabs.com/api
```

Every endpoint is documented under [API Reference](/api-reference&#x29;, grouped
by area, with parameters, request and response schemas, status codes, and an
interactive &#x2A;*“try it”** console you can call with your own key.

## Authentication in one line [#authentication-in-one-line]

Every request carries your public API key in the `X-API-KEY` header:

```bash
curl https://app.lettrlabs.com/api/v1/me \
  -H "X-API-KEY: your_api_key_here"
```

You generate that key inside the LettrLabs app — the full walk‑through is in
[Authentication & API keys](/authentication-api-keys).

## Next steps [#next-steps]

1. [Generate an API key](/authentication-api-keys) and make your first
   authenticated call to `GET /v1/me`.
2. Follow the [order of operations](/order-of-operations) to send your first
   order end to end.
3. Not sure whether to drive orders yourself or let the app? See
   [Automations vs. creating an order](/automations-vs-creating-an-order).
4. Explore the full [API Reference](/api-reference) and try requests live.