Osso

Osso exposes a REST API for managing IDP configurations, OAuth2 clients, and tenant domains. API keys are used for authentication. Endpoints cover creating/updating identity providers, listing configured domains, and admin token management. The OAuth2 broker endpoint handles the SAML auth flow transparently. SDK support is minimal — direct API calls are the pattern. The API surface is small and focused on IDP lifecycle management rather than user management.

Standard HTTP error codes. Limited documentation on specific error formats. The Ruby-based service returns JSON errors for API endpoints. SAML assertion failures are handled internally. No retry-after or rate limit documentation found. Self-hosted stability depends on deployment configuration. Error handling documentation is sparse.

Osso is an open-source SAML SSO service that acts as an OAuth2-over-SAML broker, allowing SaaS applications to offer enterprise SSO without implementing SAML directly. It provides an admin portal for managing identity provider (IDP) configurations per customer domain, and an API for programmatic IDP management. Agent relevance is moderate: agents automating B2B onboarding can use Osso's API to configure SSO for enterprise customers. Osso is primarily self-hosted (Ruby/Rails). Maintenance activity in 2026 is uncertain — the project was active in 2022-2023. Confidence is docs-derived with low certainty on current maintenance status.

Osso API uses bearer token auth with admin tokens. The admin portal handles IDP configuration UI; the API enables programmatic management. SAML assertion handling is internal — agents interact with OAuth2 flows, not raw SAML. Token scoping is limited. Self-hosted deployments are responsible for their own security posture. No built-in MFA or audit logging documented at the API level.

Documentation at ossoapp.com/docs covers setup, IDP configuration guides (Okta, Azure AD, Google), and API reference. Quality was solid as of the last known update. The project is open-source — GitHub is the authoritative source. Community support is via GitHub Issues. Given uncertain maintenance status, documentation may be partially stale. Recommended to verify current project state before adopting.