# Linq auth.md

Machine-readable authentication and registration guide for AI agents that want
to use the [Linq Partner API](https://docs.linqapp.com) — APIs for iMessage,
RCS, SMS, and Voice.

## Who this is for

AI agents (and the developers operating them) that want to send and receive
iMessage, RCS, or SMS messages programmatically via `https://api.linqapp.com/api/partner/v3`.

## Registration

Linq uses API keys. There is no OAuth authorization server today, so there is
no `/.well-known/oauth-authorization-server` or dynamic client registration.
Register through either path below:

### Option A — Sandbox signup (browser)

1. Create a free sandbox account: https://dashboard.linqapp.com/sandbox-signup
2. Generate an API key in the dashboard.

### Option B — Linq CLI (terminal, agent-friendly)

The CLI supports a non-interactive signup flow designed for agent shells:

```bash
npm install -g @linqapp/cli@latest   # requires Node 22+
linq signup
linq tokens                          # prints API credentials
```

Full verified walkthrough: https://linqapp.com/cli (markdown available via
`Accept: text/markdown`).

## Using credentials

Send your API key as a bearer token on every request:

```http
GET /api/partner/v3/chats HTTP/1.1
Host: api.linqapp.com
Authorization: Bearer <YOUR_API_KEY>
```

- Supported method: `Authorization: Bearer` header only. Keys are never
  accepted in query strings.
- Keys are scoped to your account; sandbox keys can message only verified
  handles until you upgrade.
- Rotate or revoke keys any time from https://dashboard.linqapp.com.

## Machine-readable resources

- OpenAPI spec: https://cdn.linqapp.com/openapi/linq-api-v3.yaml
- API catalog (RFC 9727): https://linqapp.com/.well-known/api-catalog
- Docs for LLMs: https://docs.linqapp.com/llms.txt and https://docs.linqapp.com/llms-full.txt
- Authentication docs: https://docs.linqapp.com/getting-started/authentication/index.md
- MCP server: `npx -y @linqapp/sdk-mcp@latest` (card at
  https://linqapp.com/.well-known/mcp/server-card.json)
- Status: https://status.linqapp.com/api/v2/status.json

## Support

Humans and agents can reach us via https://linqapp.com/s/talk-to-an-expert or
https://help.linqapp.com.