> ## Documentation Index > Fetch the complete documentation index at: https://docs.authsignal.com/llms.txt > Use this file to discover all available pages before exploring further. # Authsignal APIs > Get started with Authsignal APIs Authsignal maintains the following APIs for developers to call in their applications. ## Server API The [Server API](/api-reference/server-api) is the primary API required for any Authsignal integration. **Key features:** * Obtain a short-lived URL for the [pre-built UI](/implementation-options/prebuilt-ui/overview) * Obtain a short-lived token for a [Client SDK](/sdks/client) or the [Client API](/api-reference/client-api/overview) * Perform CRUD operations to programmatically manage a user's authenticators * Can be called directly or via a [Server SDK](/sdks/server) ## Client API The [Client API](/api-reference/client-api) is available as an alternative to the [pre-built UI](/implementation-options/prebuilt-ui/overview) if you prefer to implement your own custom or native UI. If using passkeys or push authentication, we recommend using our [Web SDK](/sdks/client/web/setup) or [Mobile SDKs](/sdks/client/mobile/setup) rather than using our Client API directly. These SDKs provide an implementation layer on top of the Client API and simplify the integration model. **Key features:** * Suitable for both web apps and native mobile apps * Supports a variety of authentication methods including passkeys, authenticator app, SMS or WhatsApp OTP, email OTP or magic link, and push authentication * Must be used together with the [Server API](/api-reference/server-api) for a complete integration * Can be called directly or via a [Client SDK](/sdks/client) ## Management API The [Management API](/api-reference/management-api) can be used to manage your tenant configuration. **Key features:** * Manage tenant configuration * Manage action and rule configuration * Manage theme and branding configuration * Can be called directly or via our [terraform provider](/advanced-usage/using-terraform)