> ## Documentation Index
> Fetch the complete documentation index at: https://docs.echozero.app/llms.txt
> Use this file to discover all available pages before exploring further.

# Quickstart

> Authenticate and call the Echo Zero MCP API in minutes.

This quickstart walks through the fastest path from zero to a working API call. Detailed guides for OAuth, HMAC signing, and signal envelopes are linked at the end.

## Prerequisites

* An Echo Zero developer account — sign in at [devportal.echozero.app](https://devportal.echozero.app)
* An API key **or** OAuth access token (see [OAuth guide](/guides/oauth) and [API keys + HMAC](/guides/api-keys-hmac))
* `curl` or any HTTP client

## 1. Verify the API is up

```bash theme={null}
curl -sS https://mcp.echozero.app/api
```

You should receive a JSON health response.

## 2. Authenticate a request

Send your API key on every authenticated REST call:

```bash theme={null}
export EZ_API_KEY="ez_live_..."

curl -sS https://mcp.echozero.app/api/v1/users/me \
  -H "x-api-key: $EZ_API_KEY"
```

OAuth-based clients can send `Authorization: Bearer <access_token>` instead. See the [OAuth guide](/guides/oauth).

## 3. Explore the API reference

Open the **API Reference** tab in the sidebar to browse endpoints, request bodies, and response schemas. The reference is generated from the live OpenAPI spec at `https://mcp.echozero.app/api/docs-json`.

## 4. Connect via MCP (optional)

For AI assistant integrations, see the [MCP Server guide](/guides/mcp). Your client should `POST` to:

```
https://mcp.echozero.app/mcp
```

Use the same API key or OAuth token on `initialize` and subsequent requests. Directory metadata lives at `https://mcp.echozero.app/public/index.json`.

## What's next

<CardGroup cols={2}>
  <Card title="OAuth 2.1" icon="key" href="/guides/oauth">
    Authorization code + PKCE for assistant clients.
  </Card>

  <Card title="Signal envelope" icon="wave-square" href="/guides/signal-envelope">
    Event types, idempotency, and delivery semantics.
  </Card>

  <Card title="Webhook security" icon="shield" href="/guides/webhook-security">
    HMAC verification and replay protection.
  </Card>

  <Card title="Sandbox" icon="flask" href="/guides/sandbox">
    Test integrations without production side effects.
  </Card>
</CardGroup>