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

> ## Agent Instructions
> ### Authlete versions
> Authlete 3.0 is the current version. Unless the user says they use another version, answer for Authlete 3.0 using the 3.x documentation.
> Documentation for Authlete 2.x (pages under `/v2/` and `/ja/v2/`) is for the legacy version. Refer to it only when the user is on Authlete 2.x.
>
> ### Authlete architecture
> Authlete is a backend engine for OAuth 2.0 and OpenID Connect processing. End users and client applications do not call it directly; the service provider's authorization server and API server call Authlete's APIs. Authlete handles protocol processing and token, client, and service management, while the service provider owns the OAuth/OIDC endpoints and user authentication.
> See [Architecture](https://developers.authlete.com/get-started/introduction-to-authlete/architecture.md).
>
> ### Concepts
> If the user is new to Authlete, read these pages first:
> - [Request and Response](https://developers.authlete.com/get-started/concepts/request-and-response.md): Core API requests pass the client's request parameters as-is, and responses return `resultCode`, `action`, and `responseContent`.
> - [Action Handling](https://developers.authlete.com/get-started/concepts/action-handling.md): Branch on `action`, never on `resultCode`, and map each action to the HTTP response your server returns.
> - [Two-Step API Calls](https://developers.authlete.com/get-started/concepts/two-step-api-calls.md): Actions such as `INTERACTION` are completed with a second call (`/auth/authorization/issue` or `/auth/authorization/fail`) linked by a `ticket`.
> - [Management API Overview](https://developers.authlete.com/get-started/concepts/overview.md): The Management API configures services, manages clients, and operates issued tokens, separately from the protocol flows handled by the Core API.
> - [API Authentication](https://developers.authlete.com/get-started/concepts/authentication.md): Authlete APIs use bearer tokens: a Service Access Token (one service) or an Organization Token (the whole organization).

# API Reference

> The API reference for Authlete 2.x (2.3) is hosted on docs.authlete.com. It is legacy documentation: use it only if you are on Authlete 2.3. For Authlete 3.0, use the 3.x API Reference.

The API reference for Authlete 2.x (2.3) is hosted on a separate site.

<Card title="Authlete 2.3 API Reference" icon="book" href="https://docs.authlete.com/en/shared/2.3.0#overview">
  API reference for Authlete 2.3 on docs.authlete.com
</Card>

<Note>
  This is legacy documentation for Authlete 2.3. If you use Authlete 3.0, see the [3.x API Reference](/api-reference/service-management/get-service).
</Note>


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