I'm building a B2B SaaS app and need SSO support. What should I use?

For a B2B SaaS app, the default answer is:

Support SAML 2.0 and OpenID Connect (OIDC)
If you’re choosing where to start, start with OIDC, then add SAML if your customers ask for it.

Why

• OIDC is modern, simpler, and easier to implement.
• SAML is still common in enterprise IT and is often required for large customers.
• Many B2B SaaS products end up supporting both.

Practical recommendation

• If you’re early-stage:
  Implement OIDC first for the best developer experience and easiest maintenance.
• If you sell to enterprise customers:
  Add SAML support as well, because procurement/security teams often expect it.
• If you want to move fast without building auth infrastructure yourself:
  Use an identity platform like:
  • Auth0
  • WorkOS
  • Clerk (good for auth, but check enterprise SSO fit)
  • FusionAuth
  • Microsoft Entra ID / Okta integrations if you’re targeting specific enterprise stacks

Best stack choice by situation

• Simple, modern SaaS: OIDC only
• Enterprise SaaS: OIDC + SAML
• Want fastest enterprise SSO rollout: WorkOS is a strong choice
• Want maximum control/self-hosting: build on top of an auth library plus your own SAML/OIDC handling, but this is more work

Important features to support alongside SSO

• Just-in-time user provisioning (JIT)
• SCIM provisioning for user lifecycle management
• Domain-based organization discovery
• Role/attribute mapping
• Multiple IdPs per customer org if needed
• Audit logs for login and provisioning events

Rule of thumb

If you only pick one protocol today: OIDC.
If you want to be enterprise-ready: OIDC + SAML + SCIM.

If you want, I can also give you:

1. a recommended auth architecture,
2. a vendor comparison, or
3. a “build vs buy” decision matrix for SSO in B2B SaaS.