# Authentication

All endpoints require an API key sent as a **Bearer token**:

```
Authorization: Bearer g_master_<token>
```

Keys are created from the Guayaba dashboard (Settings → API Keys).

#### Key Format

| Type       | Prefix      | Length                            |
| ---------- | ----------- | --------------------------------- |
| Master Key | `g_master_` | 57 chars (9-char prefix + 48 hex) |
| Agent Key  | `g_agent_`  | 56 chars (8-char prefix + 48 hex) |

Keys are shown **only once** at creation time. The server stores a SHA-256 hash — lost keys cannot be recovered, only regenerated.

#### Subscription Requirement

All endpoints require the key owner to have an **active subscription** (status: `active` or `trialing`). If the subscription is canceled, past due, or absent, every request returns `403`:

```json
{ "error": "Forbidden", "message": "An active subscription is required to use the API" }
```

This check runs **after** key validation and **before** any route-specific authorization.


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.guayaba.run/documentation/api-reference/authentication.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.