What SAML is and why it matters
Security Assertion Markup Language (SAML) is an XML-based standard used to exchange authentication and authorization data between an identity provider (IdP) and a service provider (SP). In practice, it lets users sign in once with a corporate account and gain access to multiple browser-based applications without re-entering credentials for every service. SAML is widely used in enterprises and educational institutions because it supports centralized identity management, single sign-on (SSO), and strong integration with existing directory systems like Active Directory.
How SAML works, in simple terms
SAML follows a browser redirect flow. When a user tries to open a protected application, the application redirects the browser to an identity provider to verify identity. The IdP authenticates the user (for example, by username/password or MFA) and then issues a SAML assertion , a signed XML document that states who the user is and what they’re allowed to do. The browser returns that assertion to the application, which validates the signature and grants access. Because assertions are signed and can be encrypted, SAML is suitable for environments that need strong trust between organizations and applications.
Key SAML components
- Identity Provider (IdP): verifies users and issues assertions.
- Service Provider (SP): relies on assertions to grant access.
- Assertion: signed XML containing authentication/attribute statements.
- Metadata and certificates: exchanged ahead of time to establish trust.
Common alternatives to SAML and what they do differently
Several other standards and approaches address authentication and authorization, each optimized for different use cases. The most common alternatives are OAuth 2.0, OpenID Connect (OIDC), and json Web Tokens (JWT). There are also more traditional directory and network protocols like LDAP and Kerberos. Choosing between them often depends on whether you need browser-based SSO, API authorization, mobile-friendly flows, or lightweight token exchange.
OAuth 2.0
OAuth 2.0 is an authorization framework, not an authentication protocol by itself. It defines how an application can obtain limited access to resources on behalf of a user by issuing access tokens. Because OAuth focuses on delegating access to APIs rather than asserting identity, it’s popular for mobile apps, single-page applications, and service-to-service calls. If your goal is protecting APIs or allowing third-party apps to act for a user, OAuth is usually a better fit than SAML.
OpenID Connect (OIDC)
OpenID Connect builds on OAuth 2.0 to provide authentication. It issues ID tokens (JWTs) that contain user identity information and can be validated by applications. OIDC is typically easier to work with than SAML for modern web and mobile apps because it uses JSON instead of XML and fits naturally into API-driven architectures. For new projects that need SSO and support for mobile or JavaScript-heavy frontends, OIDC often offers a more developer-friendly path.
JWT-based sessions and API tokens
JSON Web Tokens (JWTs) are a compact, url-safe way to represent claims between parties. They’re commonly used in OIDC and in custom authentication systems to maintain stateless sessions. JWTs are lightweight and work well in microservices or server-to-server communication, but they lack built-in mechanisms for encryption or revocation unless combined with additional patterns such as short token lifetimes or token introspection.
LDAP and Kerberos
LDAP (Lightweight Directory Access Protocol) and Kerberos are legacy protocols still common inside corporate networks. LDAP provides directory services and can be used for authentication lookups, while Kerberos supports ticket-based authentication in Windows domains and other environments that require fast, network-level identity verification. These options are less suited for modern cloud-based SSO across different organizations but remain core for on-premises identity infrastructures.
When to choose SAML instead of the alternatives
SAML is a good choice when you need browser SSO across enterprise applications, especially in federated environments where trust is established between distinct organizations. It’s well suited to integrations with legacy enterprise applications and identity providers that already rely on XML metadata and certificate-based trust. If your primary users access applications from corporate desktops, your identity team uses solutions like Active Directory Federation Services (ADFS), and you require strong attribute assertions, SAML is often the practical standard to implement.
When to pick OAuth or OpenID Connect
Choose OAuth when the main requirement is secure API access or delegated authorization , for example, when mobile or third-party apps need tokens to call backend services. Choose OpenID Connect when you need authentication for modern web and mobile applications with easier integration and JSON support. OIDC tends to be faster to adopt for developers, better supported in SDKs, and more flexible for hybrid applications that mix browser sessions with API calls.
Security and operational differences
All these standards can be implemented securely, but each has trade-offs. SAML’s signed assertions and certificate model provide strong non-repudiation and work well with enterprise PKI. OIDC and OAuth use JWTs and https-based token flows that fit cloud architectures and microservices. From an operational standpoint, SAML often requires more configuration up front (exchange of metadata, certificate rotation plans), while OAuth/OIDC can be easier to iterate on with modern tooling. Consider token lifetime, revocation strategies, and multi-factor authentication when comparing risk and manageability.
Implementation complexity and tooling
Implementing SAML typically involves configuring metadata files, handling XML processing, and managing cryptographic keys and certificates. Many identity providers and service providers offer turnkey solutions and libraries to reduce the burden, but debugging SAML flows can be harder due to XML and redirects. OAuth and OIDC have broad SDK support across languages and frameworks, making prototyping and maintenance faster. If you’re starting a greenfield project focused on mobile or single-page apps, OAuth/OIDC will usually reduce development time.
Practical checklist for choosing the right approach
- If you need enterprise browser SSO across organizations and many legacy apps: lean toward SAML.
- If you need mobile support, API access, or developer-friendly tokens: pick OAuth or OIDC.
- If your environment is primarily on-premises Windows/Active Directory: consider Kerberos/LDAP integrations or using SAML with your IdP.
- If you plan to support both browser SSO and APIs, consider a hybrid approach: SAML for legacy SSO and OIDC/OAuth for modern services.
migration tips if you’re moving away from SAML
migrating from SAML to OIDC/OAuth is common as teams modernize. Start by inventorying applications and classifying them by type (browser-only, API, mobile). For each app, check whether the provider supports OIDC or OAuth; if not, consider using an identity gateway that translates between SAML and OIDC. Test token lifetimes and revocation behavior, and plan for certificate and key rollover. Communicate changes to users and support teams, and phase the migration so critical services remain stable while you validate new flows.
Summary
SAML remains a solid, secure choice for enterprise browser SSO and federated identity between organizations, especially where existing infrastructure relies on XML and certificate-based trust. For API access, mobile apps, and new web applications, OAuth 2.0 and OpenID Connect offer a more modern, developer-friendly approach based on JSON and shorter token lifecycles. Choose based on your environment, needed integrations, and whether you prioritize legacy compatibility or cloud-native simplicity.
frequently asked questions
Is SAML better than OAuth for single sign-on?
SAML is often better when the goal is browser-based SSO across enterprise applications and existing identity providers. OAuth is not an authentication protocol by itself, so for pure authentication you’d typically use OpenID Connect, which builds on OAuth to provide user identity in a way that suits modern apps.
Can SAML and OIDC coexist?
Yes. Many organizations run both: SAML for legacy enterprise apps and OIDC/OAuth for new mobile and API-driven services. Gateways and identity providers can translate between protocols to smooth migration and interoperability.
Which is easier for developers: SAML or OIDC?
OpenID Connect is generally easier because it uses JSON, RESTful flows, and has broad SDK support across platforms. SAML uses XML and can require more configuration, so it typically has a steeper learning curve for developers.
Are JWTs secure enough compared to SAML assertions?
JWTs are secure when used correctly: sign tokens, use HTTPS, keep lifetimes short, and implement revocation where needed. SAML assertions offer strong signing and encryption models and are favorable in environments that require certificate-based federation. Security depends more on implementation details than on the token format alone.
