> For the complete documentation index, see [llms.txt](https://docs.aurinko.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.aurinko.io/authentication/oauth-flow.md).

# OAuth Flow

Aurinko provides a Unified OAuth Flow that is backed by providers' OAuth2 (i.e. Google, Office 365, Zoho Mail, Salesforce, HubSpot, SugarCRM) or by secure password-based authentication (i.e. MS Exchange, IMAP accounts).

There OAuth flows are available:

1. [Account](/authentication/oauth-flow/account-oauth-flow.md) - User delegated authorization that produces an Aurinko account and an access token.
2. [Service Account](/authentication/service-accounts.md) - Admin/Org-level authorization that produces an Aurinko service account and an access token.
3. [User Session](/authentication/oauth-flow/user-oauth-flow.md) - User delegated authorization that produces an Aurinko User, its primary account, and a user session token or cookie.