OIDC vs SAML: Which SSO Protocol Should You Choose?

Most teams treat the OIDC vs. SAML question as a technology preference. Developers like OIDC because it’s JSON and modern. Security teams defend SAML because it’s what the enterprise already runs. Then the product ships, and the first large customer’s IT team asks for the protocol you didn’t build.

The better question is not “which protocol is better?” It is “Who has to connect to us? From what kind of app, and what does their identity provider already speak?”

This guide covers what SAML and OIDC are, the real technical differences, and a practical framework for when to use SAML vs. OIDC. It also covers the mistakes that turn an SSO rollout into a rework project.

What is SAML and OIDC?

Both protocols do the same core job. A user signs in once with an identity provider (IdP), such as Okta, Microsoft Entra ID, or Google Workspace. The IdP then vouches for that user to an application (the service provider or relying party), so the user doesn’t need a separate password there.

=> SAML 2.0

Security Assertion Markup Language (SAML) 2.0 was ratified by OASIS in 2005. It was designed for browser-based web SSO in enterprises.

• The IdP issues an XML assertion describing the user and their attributes.
• The assertion is digitally signed with XML Signature and optionally encrypted.
• It usually reaches the application through the user’s browser via an HTTP POST or redirect.
• Trust is set up by exchanging metadata files that contain endpoints and certificates.

=> OpenID Connect (OIDC)

OpenID Connect was finalized by the OpenID Foundation in 2014. It is an identity layer built on top of OAuth 2.0.

• The IdP (called the OpenID Provider) issues an ID token, which is a signed JSON Web Token (JWT).
• Apps typically use the Authorization Code flow with PKCE, which works for web, mobile, and single-page apps.
• Configuration can be discovered automatically from a standard /.well-known/openid-configuration
• The same flow can also return OAuth access tokens for calling APIs.

A common confusion: OAuth 2.0 alone is an authorization framework. It lets an app access resources on a user’s behalf. It does not reliably tell the app who the user is. OIDC adds that authentication layer. “Login with OAuth” without OIDC is a known anti-pattern.

Read more: How to Enable Enterprise SSO with Auth0 and Azure AD (in 20 Minutes)

What is the Difference Between SAML and OIDC?

The biggest difference between SAML and OIDC is the environment each was built for. SAML assumes a browser and an enterprise web app. OIDC assumes a mix of web apps, native apps, and APIs. Here is an OIDC vs SAML comparison across the factors that matter in practice:

• Tokens and Parsing

SAML’s XML assertions are verbose. They are also notoriously difficult to validate securely. XML Signature Wrapping attacks have repeatedly broken SAML libraries because the signed element and the element the app actually reads can differ. JWTs are smaller and easier to parse. However, OIDC implementations still fail when they skip checks on the signature algorithm, issuer, audience, or expiry.

OWASP SAML Security Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/SAML_Security_Cheat_Sheet.html

• Session and Logout

SAML defines Single Logout, but it is widely considered brittle in real deployments. OIDC has separate specifications for RP-initiated, front-channel, and back-channel logout. These are more flexible, but IDP support for them varies. With either protocol, test logout explicitly. It is the part teams most often assume will “just work.”

• What neither Protocol does

Neither SAML nor OIDC handles user provisioning and deprovisioning. Creating, updating, and removing accounts when employees join or leave is the job of SCIM (System for Cross-domain Identity Management). Enterprise buyers increasingly ask for SSO and SCIM together.

When to Use SAML vs. OIDC?

Use the answers to three questions: who connects to you, what you’re building, and what already exists.

=> Choose SAML when…

• You sell B2B software to large enterprises. Many corporate IT teams have standardized SAML onboarding. Some older or on-premises IdPs, such as legacy AD FS setups, are SAML-first.
• You’re integrating with an existing SAML federation. Examples include higher education and research federations and many government environments.
• The app is a traditional server-rendered web application with no mobile client and no public API.

=> Choose OIDC when…

• You’re building mobile apps, single-page apps, or APIs. OIDC with PKCE was designed for these; SAML was not.
• You need both login and API authorization. OIDC and OAuth 2.0 share one flow and one token infrastructure.
• You control both sides of the integration, such as internal apps or consumer login, and have no customer IDP constraint.
• You’re building new infrastructure and want simpler configuration and wider library support in modern frameworks.

=> Support both when…

If you’re a B2B SaaS company, the honest answer to “SAML vs. OpenID Connect” is often both. Your own apps use OIDC internally. Your enterprise customers connect with whichever protocol their IdP prefers.

The standard way to do this is an identity broker, such as Keycloak, Auth0, Okta, or Entra ID. The broker accepts SAML or OIDC from customer IdPs and presents a single OIDC interface to your application. Your code then handles one protocol, and customer onboarding becomes configuration work.

Connecting customer IdPs, a broker, and your own applications is an integration problem as much as a security one. NextGenSoft’s software integration services cover this kind of multi-system identity work.

5 SSO Protocol Mistakes Teams Make

1. Treating SAML as legacy and skipping it. SAML is older, but it is not deprecated. It remains the default enterprise SSO language, and skipping it can block enterprise deals.
2. Using OAuth 2.0 as a login protocol. An access token is not proof of identity. If you need to know who the user is, use OIDC’s ID token.
3. Hand-rolling SAML validation. Use a well-maintained, actively patched library, and track its security advisories. Signature-bypass flaws in SAML libraries are a recurring vulnerability class.
4. Choosing a protocol before checking customer requirements. Ask sales and customer success which IdPs your target accounts use before engineering commits to one protocol.
5. Forgetting provisioning and logout. SSO without SCIM leaves orphaned accounts when employees leave. Untested logout leaves live sessions after users think they’ve signed out.

Choosing Between OIDC vs. SAML: A Decision Checklist

Before you commit, answer these questions:

• Do enterprise customers require a specific protocol in their security questionnaires?
• Will you ship mobile, desktop, or single-page clients now or within 18 months?
• Do you need to secure APIs with the same identity system?
• Do you have a broker or identity platform, or will you implement protocols directly?
• Who owns the certificate and key rotation, and how will expiry be monitored?
• Is SCIM provisioning in scope?

If you answer “yes” to both enterprise requirements and mobile or API needs, plan for a broker-based architecture that supports both protocols from day one.

Conclusion

The OIDC vs. SAML decision isn’t about which protocol is newer. It’s about fit. SAML is the lingua franca of enterprise web SSO. OIDC is the better foundation for mobile apps, SPAs, and APIs. For most B2B products, the right architecture supports both, with a broker that keeps your application code simple.

Get the requirements right first: customer IDPs, client types, API needs, provisioning, and logout. The protocol choice usually follows from there.

Planning SSO for your product or modernizing an existing identity setup? Talk to NextGenSoft’s engineering team” about designing an authentication architecture that works for your enterprise customers and your roadmap.

FAQs

1. Is OIDC more secure than SAML?
Answer: Neither protocol is inherently more secure. Both rely on signed tokens and are secure when implemented correctly. SAML’s XML signature handling is historically more error-prone, while OIDC risks come mainly from incomplete JWT validation. Library quality and correct configuration matter more than the protocol choice.

2. Can SAML and OIDC be used together?
Answer: Yes. Many organizations run both, often through an identity broker that accepts SAML or OIDC from external identity providers and issues OIDC tokens to internal applications.

3. Is SAML being replaced by OIDC?
Answer: OIDC is the default for new applications, especially mobile and API-driven ones. However, SAML remains deeply embedded in enterprise and government identity systems and is not deprecated. Expect both to coexist for years.

4. What is the difference between OAuth and OIDC?
Answer: OAuth 2.0 handles authorization: it grants an application access to resources. OIDC is built on OAuth 2.0 and adds authentication, telling the application who the user is through a signed ID token.

5. Does SAML work for mobile apps?
Answer: It can, but awkwardly. SAML depends on browser redirects and POSTs, so mobile apps must hand off to a browser and bridge the result back. OIDC with PKCE is purpose-built for native and mobile apps.