SAML or OIDC: Which is Better For Your Business?

SAML and OIDC are the two protocols that power most single sign-on in production today. They solve overlapping problems, they often coexist in the same identity stack, and the choice between them is rarely "which is better" and usually "which fits this use case." Picking right the first time saves a lot of pain.

What each protocol is

SAML

Security Assertion Markup Language. Standardised in 2005. XML-based. Designed in an era of browser-based enterprise web apps and federation between corporate domains. The dominant SSO protocol in enterprise IT for nearly two decades.

OIDC

OpenID Connect. Standardised in 2014. Built as a thin identity layer on top of OAuth 2.0. JSON-based, designed for modern web and mobile applications, native and SPA frontends, and API-driven architectures.

How they differ in practice

• Data format. SAML uses XML and digital signatures. OIDC uses JSON and JWTs.
• Transport. SAML uses browser-redirect POST bindings. OIDC uses standard HTTPS with JSON.
• Client support. SAML is web-first and awkward outside the browser. OIDC works cleanly on web, native mobile, SPA, smart TV, and machine-to-machine.
• Token size. SAML assertions can be large (kilobytes of XML). JWTs are compact.
• Developer ergonomics. OIDC is simpler to implement correctly. SAML has more edge cases and more historical implementation bugs.
• Vendor support. Both are universally supported by enterprise identity providers.

When SAML is the right choice

• You sell to enterprises and the buyer's IdP (Entra ID, Okta, Ping) already federates everything via SAML.
• You integrate with legacy enterprise apps that only speak SAML.
• The integration is browser-only and human-initiated.
• The procurement team has a SAML compliance checkbox.

When OIDC is the right choice

• You build mobile, SPA, or native apps.
• You need API authentication, not just browser SSO.
• You are starting fresh and have a choice.
• You want to combine sign-in with authorization scopes for APIs.
• Your audience includes consumers, not just enterprise users.

The realistic answer: both

Most production identity stacks end up supporting both protocols. A consumer-facing product uses OIDC. The enterprise sales team needs SAML for the procurement-required SSO integrations. The same identity provider can speak both, and good ones make it easy to expose the same user pool through either protocol depending on the relying party.

The choice that actually matters is which protocol you build for first, and that comes down to audience. Building a developer-tools company? Start with OIDC, add SAML once enterprise contracts arrive. Selling to Fortune 500 from day one? Start with SAML, add OIDC as you build mobile or partner-facing experiences.

The implementation pitfalls

Both protocols have produced their share of CVE-grade implementation bugs. The recurring ones:

• SAML signature wrapping. Verify signatures over the right element. Use a well-tested library.
• OIDC token validation. Validate issuer, audience, signature, and expiry. Reject "none" algorithm tokens.
• Redirect URI handling. Allowlist exact URIs, not patterns. Both protocols have been broken by loose redirect handling.
• Replay protection. Honour the nonce, jti, and assertion ID.
• Clock skew. Both protocols are sensitive to it. Be generous but bounded.

The bottom line

SAML and OIDC are tools. Pick the one that fits the audience and use case in front of you, and assume you will eventually need the other. The protocol matters far less than implementing whichever one you pick correctly.