SAML vs OAuth 2.0 vs OpenID Connect: Which Should Your SaaS Support for Enterprise SSO?

If an enterprise prospect asks if your SaaS supports single sign-on (SSO), it becomes a product decision and not an engineering one. Before investing development time in your team to understand SAML vs. OAuth, and which integrations enterprise customers expect, you need to know where OpenID Connect falls in the scheme and how it fits in.

If you are a B2B SaaS that is targeting the upmarket, a sensible strategy is to consider SAML 2.0 and OpenID Connect for enterprise SSO and, if it makes sense given the requirements, SCIM provisioning. OAuth 2.0 is vital for API access and delegated access, but it should not be considered as an independent user authentication protocol.

A digital and design company such as Xcentic Services can assist SaaS teams when planning and integrating authentication capabilities into a software development project. The right implementation should allow for customer identity providers, should not compromise tenant boundaries, and should also integrate into the product's architecture, but not necessarily result in additional product maintenance.

SAML vs OAuth vs OpenID Connect: Quick Comparison

Federated identity is managed by SAML 2.0, access to protected resources is managed by OAuth 2.0, and OpenID Connect is an extension of OAuth 2.0 for identity. These protocols are useful to address different issues than one another, and sometimes a SaaS product will require more than one.

The protocol descriptions above are based on the OpenID SAML 2.0 specification, the IETF OAuth 2.0 specification, RFC 6749 and the OpenID Connect Core 1.0 specification.

What's the Difference Between SAML, OAuth 2.0 and OpenID Connect?

SAML, OAuth 2.0 and OpenID Connect are all about the problem each is trying to solve. In a SAML exchange, an identity assertion is passed between parties; in an OAuth 2.0 exchange, the exchange of access to a protected resource is granted; with OIDC, a message providing information about an authenticated user is passed.

1. SAML 2.0: Enterprise identity federation

Security Assertion Markup Language (SAML) is a standard that allows for the exchange of authentication, attribute, and authorization assertions, using XML format. Enterprise SSO is when the identity provider (IdP) authenticates the user and returns a SAML response that includes an assertion, which is verified by the SaaS application.

For instance, a company's IT administrator could establish a SAML relationship between Microsoft Entra ID and your SaaS product. Then employees can sign in using the identity system of their organisation, instead of having to have a separate password for your application.

Your SaaS needs to verify the response, validate the signature and intended audience of the assertion and implement any time or issuer/recipient restrictions.

1. OAuth 2.0: Delegated authorization

OAuth 2.0 is not an authentication protocol; it's an authorization framework. In October 2012, the IETF published a specification called RFC 6749, which outlines how a client may gain limited access to a protected resource, subject to proper authorization.

A customer might integrate your SaaS with another service and allow that other service to access certain records. Access is restricted by OAuth scopes; access token gives client permission to call authorised APIs.

OAuth 2.0 does not prescribe any particular method for an application to prove its identity. This difference is relevant when creating login flows. An OAuth Token Exchange does not mean that the consumer of your application has been authenticated.

See Xcentric's guide to API security best practices for more information about API access controls and API scopes.

1. OpenID Connect: Authentication built on OAuth 2.0

OpenID Connect extends OAuth 2.0 to include an identity layer that enables a client to confirm the identity of a user and get standardised claims about their identity. It's an ID token in the form of a JWT with claims related to the authentication event and the user.

For any modern SaaS application, particularly when serving web applications, mobile clients and API-driven systems, OIDC is often an ideal choice. Allows for standard discovery processes that enable applications to get identity-provider configuration and signing-key information.

But, it is not sufficient to receive a JWT. The signature, issuer, audience, expiry, and other relevant claims of your application should be validated. The implementation also needs to follow the state and nonce properly to ensure the security of the sign-in process.

Is OAuth authentication or authorization?

OAuth 2.0 is used for authorisation. It allows a client to get access to limited portions of sensitive resources, whereas OpenID Connect is responsible for the identity layer used for user authentication.

Is OAuth covered by OpenID Connect?

OAuth 2.0 is not exactly the same as OpenID Connect. OIDC implements OAuth 2.0 mechanisms and introduces identity claims and ID tokens, enabling it to be used for user sign-in.

SAML vs OIDC: Which Is Better for Enterprise SSO?

Both SAML and OIDC can be used for enterprise SSO, with no clear best choice. SAML is a proven way for enterprise federation in the browser, whereas OIDC can be more easily integrated into modern web and mobile architectures.

According to Microsoft's official decision guide, both SAML and OIDC are options and describe their technical differences.

You should evaluate your SaaS based on the identity systems that can be used to access it, the authentication requirements for your application, and enterprise contract integration needs.

For SaaS companies, it's a matter of deciding if they should choose to support the protocol the prospect needs first, and then add it to future coverage as the sales funnel and customer base increase.

OIDC is not the same as OAuth. Even products that have capabilities for OAuth-based API integration can be missing OIDC login and enterprise SSO capabilities.

OAuth vs SAML: What are Enterprise Customers Actually asking for?

Enterprise buyers are often interested in seeing how a SaaS product can integrate with their existing identity provider, how they can enforce organisational sign-in policies and how it can make it easier for users to sign in. They have different exact protocol needs, and product teams must discover that before assuming a particular standard will suffice for all customers.

Microsoft Entra ID supports both SAML and OIDC. There are also application integrations for SAML described in Okta's developer documentation and application integrations for OIDC described in Google Workspace's developer documentation.

Official documentation includes:

• Microsoft Entra SAML and OIDC guidance

• Okta app integration documentation

• Google Workspace SAML app setup

The examples in the previous section show that both SAML and OIDC are relevant to enterprise integrations. They don't show that all customers are using both protocols or that the use of one protocol has a universal advantage.

Where is there still a need for SAML for enterprise customers?

Yes, some enterprise customers may still need to use SAML for application SSO, especially if they are relying on their current identity management processes around the integration of SAML. Depending on the policies and identity provider, other customers may choose to use OIDC or accept either.

For a SaaS founder, the best way to determine priority is to ask a potential customer about which IdP he uses, what security protocol his security team requires, if they need automated provisioning, and if SSO is a contractual requirement.

That talk can save your team from developing a technically capable integration that isn't addressing the procurement need.

Which SSO Protocol Should Your SaaS Support First?

A SaaS product should be based on a protocol that meets the needs of its most valuable customers and be flexible enough to accommodate the addition of another protocol in the future. Depending on the product being sold to older enterprises, SAML can be a good first step to explore, or OIDC can be a better starting point for products that are newer and API-based.

The following table is Xcentric's suggested planning template and is not an assertion of universal customer adoption.

A practical implementation roadmap

Start by documenting your target customers' requirements. Verify their identity providers, anticipated login experience, tenant model, and provisioning requirements before deciding on libraries or making database alterations.

Then, deploy one protocol with well-known libraries and an explicit authentication boundary. Add tenant-aware configuration, secure identity mapping, logging and a proven account-linking policy. Use separate identity provider configuration from application logic to allow for a second protocol without having to rewrite user management.

Last but not least, validate with customer representative identity provider configurations and describe the configuration steps for customer IT administrators. Enterprise SSO is not just a software functionality; it is also an onboarding experience.

OAuth 2.1 is also something to keep an eye on, but isn't to be touted as a final standard. The IETF has the OAuth 2.1 Authorization Framework listed as an active Internet-Draft, and has a submission to the IESG deadline of December 2026. It is not a published final RFC; it is still ‘under development’.

Do You Need SCIM as Well as Enterprise SSO?

System for Cross-Domain Identity Management (SCIM) is a standard that allows you to exchange and manage a user's identity across systems. Sign-in can be processed by SSO, and user creation, updates, and deactivation by SCIM can be automated, which is useful for enterprise account administration.

In September 2015, the core schema of SCIM was published as RFC 7643 and the protocol as RFC 7644 by the IETF. The standards define identity resources and an HTTP-based protocol to manage them. This information comes from RFC 7643, SCIM Core Schema and RFC 7644, SCIM Protocol.

Think of a business that adds or lets go of workers on a frequent basis. If a provisioning system is not used, one administrator might have to manually create accounts and keep track of the employees who leave the company. With a compatible implementation, both the identity provider and SaaS application can help to alleviate that operational burden with SCIM.

SSO and SCIM are not one and the same thing. When a customer needs to enroll multiple users in their system, they might need SCIM first and then SSO.

Build SSO In-House or Use an Identity Service?

A SaaS team should only create custom authentication infrastructure if there's a strong business need, and if they have the skills to keep it up and running. However, for many product teams, it could be sufficient to use maintained protocol libraries or a specialist identity service to achieve this, but still require the application to be correctly mapped at the tenant level, with authorisation and security controls.

There are 3 main approaches for implementation.

The choice of approach will be determined by architecture, team skills, security needs, and commercial model. Never select a provider based on its support of a protocol.

Common Implementation Mistakes in Multi-Tenant SaaS

Multi-tenant SSO isn't simply an integration between an identity provider and a login screen. For each identity-provider configuration, the application should link it to an appropriate customer tenant, and ensure that a successful sign-in does not allow access to data from another organisation. In the design and testing, some implementation points must be taken into account.

1. Tenant and identity mapping: Store each customer's IdP configuration in a tenant-aware model. Avoid relying on an unverified email domain or a request parameter supplied by a tenant to identify a tenant. Linking of accounts should be voluntary and protected.

1. Signature and token validation: Validate signatures for SAML, audience for SAML, issuer for SAML, recipient for SAML, destination for SAML, and time restrictions for SAML, as needed based on the SAML profile. In the case of OIDC, check the ID token's signature, issuer, audience, expiry, and associated nonce. Do not hand-write cryptographic validation.

1. Provisioning and account lifecycle: Specify the actions to take when the user is invited, when the provisioning is done in real time, when the user is disabled, and when the user is removed by the customer. Not all problems with account lifecycle are solved by SSO, and SCIM also requires its own authorisation and validation mechanisms.

1. Clock skew and expiry: If a server has an inconsistent clock they might reject valid assertions and/or tokens because of the time it expects. Use a bounded clock-skew but not a bounded time. Use bounded clock-skew, but not bounded time for clock-skew, whilst maintaining expiry and replay protection.

1. Logout behaviour: Specify what will happen with the application sessions when a user logs out locally, and whether the identity provider supports a compatible federated log out flow. Note that if the SaaS session is terminated, not all IdP sessions are terminated.

1. Operational support: Log authentication failures without revealing tokens, assertions, secrets, or any unnecessary personal data. Clear configuration instructions & actionable error messages for customer administrators.

To see some general guidance for application security, check out web application security basics and the OWASP Top 10 2025 guide to authentication failures. See JWT vs session authentication for SaaS apps for session storage and application session design.

Integrate Enterprise SSO into your SaaS using Xcentric Services

While Enterprise SSO can be integrated into your SaaS to address customer identity requirements, SAML, OAuth 2.0 and OIDC are just the first signs of the choices you'll need to make. The implementation needs to also consider tenant isolation, secure token and assertion validation, account lifecycle management, and a reliable sign-in experience.

If you're a customer of the enterprise edition seeking SSO? When considering the implementation of SAML and OIDC, Xcentric Services will help you plan and integrate it into your SaaS product without having to rebuild authentication in an unnecessary manner.

Whatever SSO integration, SCIM provisioning, multi-tenant authentication redesign or increased SaaS development support you may need, this will start with an evaluation of your current stack and the needs of your target customers.

Reach out to Xcentric Services for a discussion on the product architecture, enterprise requirements and a realistic implementation plan.