SAML vs OAuth: What's the Difference + Which should you use?

SAML and OAuth are both standards for managing access between apps and services, but they serve very different purposes and use cases.

SAML is used in authentication and identity federation to allow users to log in once and access multiple services — often in Enterprise or Corporate scenarios.

OAuth handles authorization only and grants apps limited access to user data without sharing passwords. Its usage is much more ubiquitous than SAML

While both are commonly used in Single Sign-On (SSO), they approach it differently. SAML provides a direct SSO experience for enterprise applications, while OAuth can be part of an SSO solution when combined with protocols like OpenID Connect.

In this article, we’ll dive deep into each protocol and discuss how each works, their unique benefits, and their drawbacks to help you decide which protocol fits your needs best.

SAML vs OAuth: Which is right for you + what are they

SAML (Security Assertion Markup Language) is an authentication protocol mostly used for Single Sign-On authentication to log users into multiple apps from a single place. It uses XML-based assertions to represent authorization and authentication data.

OAuth (Open Authorization) is an authorization framework that lets apps obtain limited access to user data on other apps without having to expose user credentials. It uses access tokens and JSON to represent authorization data.

Use SAML if: You're building enterprise apps and want your customers' employees to log in from their corporate identity provider (IdP).

Use OAuth if: Your app needs to use information from another app or act on a user’s behalf.

What is SAML?

SAML is an XML-based open standard for exchanging authentication and authorization data — known as SAML assertions – between an Identity Provider (IdP) and a Service Provider (SP).

The IdP is where users authenticate. It could be a provider like Active Directory (AD), Okta, or another dedicated SAML identity provider. To log a user into an app, the IdP generates a SAML assertion that includes the user's identity, authentication status, and potentially additional attributes like roles and sends it to the SP.

The SP (the app the user wants to access) relies on the IdP to authenticate users. It consumes the SAML assertion from the IdP, and either allows or denies them access based on the identity data in the assertion.

A SAML authentication process can be initiated in two main ways:

1. Service provider-initiated SAML SSO flow:

• The user attempts to access a resource or app (SP).
• The SP redirects the user to their IdP for authentication.
• If they aren’t logged in already, the user logs in to the IdP. 
• The IdP generates a SAML assertion.
• The IdP redirects the user back to the SP with the SAML assertion.
• The SP validates the assertion and grants access if the user is authenticated and authorized.

2. Identity provider-initiated SAML SSO flow:

• The user logs into the IdP dashboard and selects an application they wish to access.
• The IdP generates a SAML assertion.
• The IdP redirects the user back to the SP with the SAML assertion.
• The SP validates the assertion and grants access if the user is authenticated and authorized.

Unlike OAuth, which is strictly an authorization framework, you can use SAML for both authentication and authorization. This is because SAML assertions can carry data that verifies a user’s identity (authorization) and information on whether they can access your app (authorization).

Pros of SAML

• SAML-based SSO allows users to access multiple apps with one login. Users don’t need to remember multiple authentication factors like passwords which significantly simplifies the login process.
• You don’t have to worry about passwords since SAML enables a central identity provider (IdP) to handle authentication. The user logs in once at the IdP, which then asserts the user's identity to your app.
• Identity providers can pack a lot of details into SAML assertions, not just identity information but also data about the user's roles, permissions, or preferences allowing for more fine-grained access control and personalized user experience.‍
• SAML is a well-established standard and innumerable companies use it to SSO users into the hundreds of apps their employees use daily. By supporting SAML SSO, you're opening the door to more paid seats from your enterprise customers.

Cons of SAML

• SAML can be complex to set up and configure. You need to understand XML and specific SAML constructs like assertions, protocols, and bindings. This setup often involves managing digital certificates for security purposes, mapping user attributes accurately between systems, and troubleshooting interoperability issues between providers.
• SAML was initially designed for web SSO and does not support modern, mobile-first apps as easily as newer standards like OpenID Connect. 
• SAML flows require redirects ( among the user's browser, the IdP, and the SP) which will introduce noticeable delays in your app.

SAML is best suited for enterprise apps where employees need to access a suite of applications from a single place. For instance, an employee can log into a central portal (the IdP) and from there can access their email, HR systems, and internal databases (SPs) without needing to log in to each service separately.

What is OAuth?

OAuth is an authorization protocol for access delegation. It lets your app request and obtain limited access to a user's data on another service, without needing their login details. It’s what allows you to access GitHub repos or Facebook posts directly without asking for a user’s username or password.

Compared to SAML, OAuth is quite lightweight — it uses JSON to represent data and simple access tokens to transmit authorization data instead of verbose XML assertions.

An access token is a compact string that grants your app permissions to a user's data for a limited time. Once the token expires, you can use a refresh token to get a new access token without asking a user to log in.

Here’s how OAuth works:

This flow differs depending on the OAuth grant flow you’re using. A grant flow defines the steps and permissions involved in authenticating and authorizing your app to access user data.  Some examples of OAuth grant flows include:

Each grant type caters to a specific type of app, like web apps, single-page apps or mobile apps. Unlike SAML, you don’t have to make one authorization flow work for all your apps.

Pros of OAuth

The main benefits of OAuth are:

• Users don't have to share their authenticating data (e.g passwords) to give your app access to their information on other services. Plus, with OAuth 2.0, if they ever change their mind, they can easily take back that permission by revoking your token.
• OAuth is flexible and can be used for various types of data access, from reading to modifying user data. It also allows users to grant limited access to their data, rather than all-or-nothing access. For example, a user can allow you to read their posts on X but not post on their behalf.

Cons of OAuth

Some of the downsides of OAuth include:

• Implementing OAuth can be complex, especially if you’re new to it. There are multiple steps and grant types involved. You need to know which grant type to use, how to securely store tokens, how to monitor token expiration, and how to request new access tokens once they expire. 
• Although OAuth itself is secure, incorrect implementation can introduce security vulnerabilities. The most common issue is insecurely storing access tokens, a hacker can steal them, masquerade as you, and gain access to a user’s sensitive data.

Some of the most common use cases for OAuth are:

• Social logins: You can use OAuth to allow users to log into your app using their existing social media accounts (Facebook, LinkedIn, GitHub, etc.)
• Third-party app access: With OAuth, your app can act on a user's behalf. For example, it can post updates to a user's social media timeline or access their cloud storage to read or write files.

What are SAML and OAuth used for?

Both SAML and OAuth are protocols used for securing access to apps and systems.

SAML is used for single sign-on (SSO) to allow users to access multiple applications from a central portal. OAuth is used for delegated access, letting you access user data from external apps without using their passwords.

FAQs

Is SAML used for authorization?

SAML is primarily used for authentication; however, a SAML assertion can also carry attributes about the user, such as roles and permissions that Service Providers (SP) can use to make authorization decisions.

What is the difference between SAML and SSO?

SAML is a standard protocol used to implement Single Sign-On (SSO). It defines a way for security information to be exchanged between an identity provider (who verifies the user) and a service provider (who needs the verification to grant access).

On the other hand, SSO is a broader concept that refers to the process that allows a user to authenticate once and access multiple apps. SAML is just one of many protocols that can enable SSO.

What is the difference between OAuth and SSO?

The key difference between OAuth and SSO is that OAuth focuses on granting access to resources without sharing credentials, while SSO simplifies the authentication process across different systems by allowing users to authenticate once and gain access to multiple apps at once.

Next steps

If your customers are a mix of enterprise clients and everyday users, you’ll most likely have to integrate with both SAML providers (like Okta, Microsoft Entra, or Ping Identity) and OAuth providers (like Google and Facebook) — SAML for enterprise SSO and OAuth for social logins.

Unfortunately, building these integrations can be a pain. Your team must have a good grasp of SAML and OAuth specifications — including how the multiple OAuth grant flows work, how to parse XML assertions, and how to properly secure everything. And even if you have SAML and OAuth experts, there's the headache of keeping up with the ever-changing policies and rates of each provider.

If you’d rather not deal with such complexities but still want to expand your customer base, use Directory Sync from WorkOS. It offers a single API-based integration for connecting to the numerous SAML and OAuth providers your potential clients use. With Directory Sync, you can concentrate on what you do best — developing your core product — while effortlessly increasing the number of customers you convert.

Explore Directory Sync by WorkOS.