[Home](./index.md) > [@firebase/auth](./auth.md) > [Config](./auth.config.md) ## Config interface Interface representing the Auth config. Signature: ```typescript export interface Config ``` ## Properties | Property | Type | Description | | --- | --- | --- | | [apiHost](./auth.config.apihost.md) | string | The host at which the Firebase Auth backend is running. | | [apiKey](./auth.config.apikey.md) | string | The API Key used to communicate with the Firebase Auth backend. | | [apiScheme](./auth.config.apischeme.md) | string | The scheme used to communicate with the Firebase Auth backend. | | [authDomain?](./auth.config.authdomain.md) | string | (Optional) The domain at which the web widgets are hosted (provided via Firebase Config). | | [sdkClientVersion](./auth.config.sdkclientversion.md) | string | The SDK Client Version. | | [tokenApiHost](./auth.config.tokenapihost.md) | string | The host at which the Secure Token API is running. |