Single Sign-on Protocols: OlDC vs OAuth2 vs SAML

Single Sign-On (SSO) is vital for seamless authentication across multiple services. Choosing the right protocol—OAuth2, OIDC, or SAML—is key. This blog explores their features, workflows, and use cases to help you implement the best SSO solution for your needs.

Oliver Kingsley

Oliver Kingsley

18 May 2025

Single Sign-on Protocols: OlDC vs OAuth2 vs SAML

Single Sign-On (SSO) has become a critical feature in modern web applications, providing users with a seamless authentication experience across multiple services. When implementing SSO, choosing the right protocol is essential to ensure security, scalability, and ease of use. Three prominent protocols used for SSO are OAuth2, OIDC (OpenID Connect), and SAML (Security Assertion Markup Language). In this blog, we will explore these protocols, their differences, and when to use each for implementing SSO.

What is SSO?

Single Sign-On (SSO) is an authentication process that allows a user to access multiple applications or services with one set of login credentials. This not only enhances user experience by reducing the need to remember multiple passwords but also improves security by centralizing authentication.

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Apidog Enterprise offers SSO integration with SAML 2.0-compatible identity providers like Microsoft Entra ID. This enhances security with regular identity verification and simplifies access through direct login and organization joining via work emails. Give it a try!
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Overview of OIDC, OAuth2 and SAML

1. OpenID Connect (OIDC)

OIDC (OpenID Connect) is an identity layer built on top of OAuth2. It provides a standardized way to authenticate users and obtain their identity information, making it a popular choice for SSO.

Key Features:

Workflow:

  1. The user authenticates with the authorization server.
  2. The authorization server issues an ID token and an access token.
  3. The client verifies the ID token to authenticate the user.
  4. The client may use the access token to request additional user information from the UserInfo endpoint.

2. OAuth2

OAuth2 (Open Authorization) is a widely used authorization framework that allows third-party applications to access a user's resources without exposing their credentials. While OAuth2 is primarily used for authorization, it can be leveraged for SSO in conjunction with other protocols.

Key Features:

Workflow:

  1. The user authenticates with the authorization server.
  2. The client application receives an authorization code.
  3. The client exchanges the authorization code for an access token.
  4. The client uses the access token to access resources on behalf of the user.

3. SAML

SAML (Security Assertion Markup Language) is an XML-based protocol used for both authentication and authorization. It is commonly used in enterprise environments for SSO and federated identity management.

Key Features:

Workflow:

  1. The user requests access to a service provider (SP).
  2. The SP redirects the user to the identity provider (IdP) for authentication.
  3. The user authenticates with the IdP.
  4. The IdP issues a SAML assertion to the SP.
  5. The SP verifies the assertion and grants access to the user.

Comparing OAuth2, OIDC, and SAML for SSO

1. Authentication vs. Authorization

2. Token Format

3. Complexity and Use Cases

4. Integration and Ecosystem

When to Use Each Protocol

OIDC

OAuth2

SAML

Enhancing API Management with Apidog's SSO

Apidog's Single Sign-On (SSO) feature enhances security and streamlines user management by allowing users to authenticate using a single set of credentials across multiple API projects. SSO simplifies access control for organizations, reducing the need for multiple passwords and decreasing the risk of security breaches. Apidog supports various SSO providers that comply with SAML 2.0, such as Microsoft Entra ID, ensuring a seamless integration process. This feature is particularly beneficial for teams and enterprises, facilitating easier collaboration and administration.

Users need to sign in with SSO set by enterprises to get access.
Intro to SSO | Apidog
Explore SSO definition and advantages.

Conclusion

Choosing the right protocol for SSO depends on your specific needs and environment. OAuth2 is excellent for authorization and access delegation, while OIDC builds on OAuth2 to provide robust authentication and identity management. SAML is the go-to solution for enterprise-level SSO and federated identity management.

For developers and IT professionals, understanding these protocols and their differences is crucial for implementing secure and efficient SSO solutions. Apidog offers SSO solutions for enterprises to manage permission control over their API project, adding extra security to the company's assets. Whether you're working on web applications, mobile apps, or enterprise systems, selecting the appropriate protocol and leveraging the right tools will enhance both security and user experience.

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