TL;DR
OAuth 2.0, OpenID Connect, and SAML are three distinct but complementary identity standards. OAuth 2.0 handles secure delegated authorization — letting apps act on a user's behalf without exposing credentials. OpenID Connect layers user authentication on top of OAuth 2.0, making it ideal for consumer-facing logins. SAML is an XML-based standard best suited for enterprise single sign-on across internal and third-party applications. Rather than choosing one, organizations should deploy all three strategically based on the operation being protected.
Comparing OAuth 2.0, OpenID Connect, and SAML
There are as many ways to keep data safe as there are ways to attack it. From multi-factor authentication to single sign-on to on-premises firewalls, the options can be staggering. For developers and information technology (IT) professionals, the choice of how to keep data and identities secure begins even sooner: choosing the standard that should be deployed to keep federated identity safe.
The decision isn't always a straightforward one. Many struggle to distinguish between Open Authorization (OAuth) 2.0, OpenID Connect, and Security Assertion Markup Language (SAML), each of which brings structure to the federation process. This article brings clarity on what these standards mean, how they compare, and the purposes for which enterprises should use them.
We've also got a more focused comparison between SAML vs OAuth in another article if that's what you're looking for.
What are the key differences between OAuth 2.0, OpenID Connect, and SAML?
The main differentiator between these three players is that OAuth 2.0 is a framework that controls authorization to a protected resource such as an application or a set of files, while OpenID Connect and SAML are both industry standards for federated authentication. That means that OAuth 2.0 is used in fundamentally different situations than the other two standards (examples of which can be seen below), and can be used simultaneously with either OpenID Connect or SAML.
Using either OpenID Connect or SAML independently, enterprises can achieve user authentication and deploy single sign-on. Though they both deal with logins, they have different strengths and weaknesses.
- OpenID Connect is built on the OAuth 2.0 protocol and uses an additional JavaScript Object Notation (JSON) Web Token (JWT), called an ID token, to standardize areas that OAuth 2.0 leaves up to choice, such as scopes and endpoint discovery. It is specifically focused on user authentication and is widely used to enable user logins on consumer websites and mobile apps.
- SAML is independent of OAuth, relying on an exchange of messages to authenticate in Extensible Markup Language (XML) SAML format, as opposed to JWT. It is more commonly used to help enterprise users sign in to multiple applications using a single login.
When should you use OAuth 2.0, OpenID Connect, or SAML?
Remember that it isn't a question of which structure an organization should use, but rather of when each one should be deployed. A strong identity solution will use these three structures to achieve different ends, depending on the kind of operations an enterprise needs to protect. Their use cases are as follows:
| Standard | Primary Purpose | Common Use Case | Format |
|---|---|---|---|
| OAuth 2.0 | Delegated authorization | Granting apps access to contacts or resources on behalf of a user | Token-based |
| OpenID Connect | User authentication | Signing in to apps via Google or Facebook | JSON Web Token (JWT) |
| SAML | Federated authentication & authorization | Enterprise Single Sign-On (SSO) for tools like Salesforce, Box, or Workday | XML |
Enterprises rely on web frameworks and protocols like OAuth 2.0, OpenID, and SAML to bring structure and security to federated identity. Knowing when to use each is a key step towards protecting your organization's data from the ground up.
Frequently asked questions
Is OAuth 2.0 an authentication protocol?
No. OAuth 2.0 is an authorization framework, not an authentication protocol. It controls access to protected resources — such as files or application data — on behalf of a user, without requiring the user to share their credentials directly. For authentication, organizations typically pair OAuth 2.0 with OpenID Connect.
Can OAuth 2.0 and SAML be used together?
Yes. OAuth 2.0 and SAML serve different purposes and can be deployed simultaneously within the same identity solution. OAuth 2.0 handles delegated authorization, while SAML manages federated authentication — particularly for enterprise single sign-on scenarios.
What makes OpenID Connect different from SAML?
OpenID Connect is built on top of OAuth 2.0 and uses JSON Web Tokens (JWTs) for identity data. It is widely adopted for consumer-facing applications and mobile logins. SAML, by contrast, is XML-based and independent of OAuth 2.0, making it the more common choice for enterprise environments where users need access to multiple internal and third-party applications.
When should an enterprise use SAML instead of OpenID Connect?
SAML is generally preferred in enterprise contexts where users need seamless single sign-on access to multiple business applications — such as Salesforce, Box, or Workday — using a single set of corporate credentials. OpenID Connect is better suited for consumer-facing web and mobile applications.
What is federated identity, and why do these standards matter?
Federated identity allows users to use a single set of credentials to access multiple systems or applications across organizational boundaries. OAuth 2.0, OpenID Connect, and SAML each bring structure and security to this federation process, helping enterprises protect data and manage user access without requiring separate logins for every service.
Do organizations need to choose between OAuth 2.0, OpenID Connect, and SAML?
No. These three standards are not mutually exclusive. A robust identity solution will typically deploy all three, using each for the specific type of operation it is best suited for — authorization, consumer authentication, or enterprise single sign-on respectively.
