In today’s digital environment, making sure authentication and authorisation are handled securely is essential for any modern application. Two major standards that help solve these challenges are OAuth 2.0 (Open Authorisation) and OpenID Connect (OIDC). Although they are often discussed together and may seem similar at first glance, it’s important, especially for developers, system architects, and security teams, to understand the key differences between them, since each serves a unique role. In this blog, we will examine the differences between the two standards, as one of them has been adopted by Singpass as part of its digital identity ecosystem.
Why is understanding the differences so important?
Without a proper understanding of both, it could lead to misapplying the protocols—such as using OAuth for authentication without OIDC—which can introduce serious security vulnerabilities like impersonation attacks. This misunderstanding may also lead to flawed or insecure implementations. A clear separation of concerns between authentication and authorisation not only helps in choosing the correct protocol but also supports the development of scalable, maintainable architectures. It ensures reliable integration with identity providers (IdPs), social login platforms, and federated identity systems.
Let’s now examine the key differences between the two standards.
OAuth 2.0 is an authorisation framework that allows third-party applications to access a user’s resources with limited permissions without requiring direct access to the user’s credentials. Its primary role is to handle authorisation, not authentication. As such, it does not provide any user identity information. The protocol issues an Access Token, which grants access to protected resources, but it does not define or include an ID Token. OAuth 2.0 is best suited for use cases where an application needs to interact with APIs or access user data on behalf of the user.
In contrast, OpenID Connect (OIDC) is an identity layer built on top of OAuth 2.0 that adds standardised authentication capabilities. It enables clients to verify a user’s identity and securely retrieve basic profile information in a consistent, interoperable way. OIDC introduces the ID Token, a JSON Web Token (JWT) that contains identity claims such as the user’s name, email, and other profile details. Unlike OAuth 2.0, which only issues an Access Token, OIDC provides both an Access Token and an ID Token, with the latter specifically intended for identity verification. OIDC is ideal for scenarios where applications need to authenticate users and access their personal profile data.
Which Protocol is right for you?
Selecting the right protocol depends on the purpose your application is meant to serve. Here are some general guidelines to help you determine whether OAuth 2.0 or OIDC is the better fit. If your application’s primary focus is to manage access to user resources without needing to confirm who the user is, then OAuth 2.0 is the appropriate choice. It is ideal when authentication is handled elsewhere, and all you need is secure access control using tokens, especially in scenarios involving APIs or backend services. On the other hand, if your application requires user login, identity verification, or access to personal details like name and email, OpenID Connect (OIDC) is more suitable. OIDC is also the better option when implementing Single Sign-On (SSO) across multiple systems.
Singpass has adopted the OpenID Connect (OIDC) protocol.
To modernise how users authenticate across digital services in Singapore, Singpass uses OpenID Connect (OIDC) to ensure smoother integration for both public and private platforms through a consistent and widely accepted approach. OIDC not only helps confirm who the user is but also supports secure access to services across web and mobile environments. It introduces ID tokens that carry trusted identity details, making interactions more secure while reducing the risk of impersonation. For developers, the protocol removes complexity by offering reliable tools and predictable structures, speeding up integration. All of this makes the application able to meet growing demands around digital identity and privacy.
Interested in learning about the basics of OpenID Connect (OIDC)? Check out this related blog here:
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