Open Source SSO

It can be, but the license line is not the full cost. Budget for infrastructure, backups, security review, upgrades, connector maintenance, and on-call response when logins fail. Open source SSO often makes sense when identity is strategic, compliance requires control, or hosted per-user pricing becomes awkward. For a small team with simple SaaS needs, managed identity may still be cheaper operationally.

Self-host when you need strict data residency, private network reachability, custom auth flows, or direct control over keys and logs. Use a hosted deployment when your team cannot staff reliable operations for a login-critical service. The key question is not ideology; it is whether you can patch quickly, restore confidently, monitor authentication failures, and survive database or node loss without locking users out.

Most teams should prioritize OIDC for modern web and mobile apps, SAML for enterprise SaaS, LDAP for older internal systems, and SCIM for provisioning. If you use VPNs, Wi-Fi, or network appliances, RADIUS may also matter. Avoid choosing around one protocol demo. Test the exact claims, groups, signing behavior, and callback flows your real applications expect.

Migration is usually phased rather than a single cutover. You import or sync users and groups, recreate application clients, map claims, test MFA policy, then move one app or department at a time. Password hashes often do not transfer cleanly unless both systems support the same format, so expect federation during transition, staged password resets, or a first-login migration flow.

Often, but not always directly. Older apps may need LDAP bind support, a reverse proxy that injects trusted headers, a SAML bridge, or custom middleware. Test deep links, logout, session timeout, API access, and background jobs that were built around local passwords. The hardest cases are apps that mix authentication and authorization in their own user tables with no external identity hook.

Look beyond whether MFA exists. Check support for WebAuthn and FIDO2, TOTP, recovery codes, device enrollment, backup factors, and step-up prompts for sensitive apps. You also need policies that vary by group, network, risk level, or application. A weak recovery process can defeat strong MFA, so review help-desk reset flows and audit trails before rollout.

No. SSO proves who the user is and can send attributes such as groups, roles, or department. The application still decides what that user can do unless it delegates authorization explicitly. Good SSO design keeps group names stable, maps claims predictably, and uses SCIM where possible to provision app accounts. Expect cleanup inside each app during migration.

Check signing key rotation, TLS configuration, secure cookies, CSRF handling, brute-force protection, admin MFA, client secret storage, and audit logging. You should be able to tell who changed a policy, added an application, issued a token, or modified a group. Also verify how emergency admin access works when your primary directory, MFA provider, or network path is unavailable.

Existing application sessions may keep working, but new logins, token refreshes, logout, and provisioning can fail. The exact blast radius depends on token lifetimes and how apps validate sessions. Plan for redundant nodes, database failover, health checks that test real login paths, and clear break-glass access for administrators. SSO should be treated like DNS or the primary database, not a side service.

You want stable APIs for users, groups, clients, policies, keys, and audit retrieval. Manual console changes do not scale once every app needs redirect URIs, claims, certificates, and group mappings. Check whether configuration can be promoted between environments and reviewed before production. SCIM support is especially useful because it reduces custom scripts for account creation and deactivation.

Back up the database, configuration, signing keys, encryption secrets, client secrets, themes, and audit logs according to your recovery requirements. A database backup without the right keys may restore users but break tokens or integrations. Test restores in an isolated environment and document how to rotate secrets after recovery. SSO backups deserve tighter access controls than ordinary application backups.

The damage depends on how standards-based your deployment is. If your apps use normal OIDC, SAML, LDAP, and SCIM, you can usually migrate with planning. The risky parts are custom plugins, themes, proprietary policy logic, and undocumented client settings. Keep exports of users, groups, application definitions, and keys, and avoid deep customization unless your team can maintain a temporary fork.