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

# Start OAuth Flow

> Start OAuth authentication flow using the Stytch Vanilla JS SDK

The `oauth.$provider.start()` methods start OAuth flows by redirecting the browser to one of Stytch's [oauth start](/api-reference/consumer/api/oauth/start) endpoints. The method will also generate a PKCE `code_verifier` and store it in local storage on the device (See the [PKCE OAuth guide](/consumer-auth/authentication/oauth/adding-pkce) for details). If your application is configured to use a custom subdomain with Stytch, it will be used automatically.

* `oauth.amazon.start()`
* `oauth.apple.start()`
* `oauth.bitbucket.start()`
* `oauth.coinbase.start()`
* `oauth.discord.start()`
* `oauth.facebook.start()`
* `oauth.github.start()`
* `oauth.gitlab.start()`
* `oauth.google.start()`
* `oauth.linkedin.start()`
* `oauth.microsoft.start()`
* `oauth.salesforce.start()`
* `oauth.slack.start()`
* `oauth.twitch.start()`
* `oauth.yahoo.start()`

## Parameters

<ParamField path="configuration" type="object">
  Additional configuration.

  <Expandable title="properties">
    <ParamField path="login_redirect_url" type="string">
      The URL Stytch redirects to after the OAuth flow is completed for a user that already exists. This URL should be a route in your application which will run oauth.authenticate (see below) and finish the login.

      The URL must be configured as a Login URL in the [Redirect URL page](https://stytch.com/dashboard/redirect-urls). If the field is not specified, the default Login URL will be used.
    </ParamField>

    <ParamField path="signup_redirect_url" type="string">
      The URL Stytch redirects to after the OAuth flow is completed for a user that does not yet exist. This URL should be a route in your application which will run oauth.authenticate (see below) and finish the login.

      The URL must be configured as a Signup URL in the [Redirect URL page](https://stytch.com/dashboard/redirect-urls). If the field is not specified, the default Signup URL will be used.
    </ParamField>

    <ParamField path="custom_scopes" type="string">
      Include a space separated list of custom scopes that you'd like to include. Note that this list must be URL encoded, i.e. the spaces must be expressed as %20.
    </ParamField>

    <ParamField path="provider_params" type="object">
      An object containing parameters that you'd like to pass along to the OAuth provider. For example, some OAuth providers support a `login_hint` parameter that allows you to pre-populate the OAuth login flow with a suggested email address. We recommend consulting each OAuth provider's documentation for a list of supported parameters. The keys in the `provider_params` object are the parameter names (like `login_hint`), and their values are the data that you'd like to pass along for each parameter (like `example_hint@stytch.com`).
    </ParamField>

    <ParamField path="oauth_attach_token" type="string">
      A single-use token for connecting the Stytch User selection from an OAuth Attach request to the corresponding OAuth Start request.
    </ParamField>
  </Expandable>
</ParamField>

## Response

<ResponseField name="success" type="boolean">
  Whether the OAuth flow was started successfully.
</ResponseField>

<ResponseField name="error" type="Error">
  The error object if the OAuth flow was not started successfully.
</ResponseField>

<ResponseField name="reason" type="string">
  If error, the reason for the error.  One of `User Canceled`, `Authentication Failed`, or `Invalid Platform`.
</ResponseField>

<Panel>
  <RequestExample>
    ```js theme={null}
    import { StytchClient } from '@stytch/vanilla-js';

    const stytch = new StytchClient('${publicToken}');

    export const startOAuth = () =>
    stytch.oauth.google.start({
      login_redirect_url: '${exampleURL}/authenticate',
      signup_redirect_url: '${exampleURL}/authenticate',
      custom_scopes: [
        'https://www.googleapis.com/auth/documents.readonly',
        'https://www.googleapis.com/auth/drive.readonly',
      ],
      provider_params: {
        login_hint: 'example_hint@stytch.com',
      },
    });
    ```
  </RequestExample>
</Panel>