What is OIDC?

What is OIDC? OIDC, or OpenID Connect, is an identity layer built on top of OAuth 2.0 that lets applications authenticate users and receive basic identity information in a standardized way. In practice, OIDC is widely used for modern login flows, single sign-on, and identity federation across web and mobile apps.

Short answer

OIDC stands for OpenID Connect. It adds authentication to OAuth 2.0 so an application can verify who a user is and receive identity claims such as a user ID, email address, or profile details.

What OIDC does

OIDC is a standardized protocol for authentication. It helps an application answer the question:

Who is the user signing in?

That is different from OAuth 2.0, which is mainly about delegated access and answers:

What is this app allowed to access?

This is why OIDC vs OAuth is such a common point of confusion. They are related, but they are not interchangeable.

For a deeper breakdown of the relationship, see /content/what-is-oauth-2-0.

Why OIDC exists

Before OpenID Connect became common, login integrations were often inconsistent, custom-built, or based on older federation approaches. OIDC gave developers and identity teams a more standard way to:

sign users in to applications
enable single sign-on
receive verified identity claims
avoid having every app manage passwords directly
integrate with external identity providers more consistently

You will often see OIDC used in:

enterprise SSO for SaaS apps
“Sign in with” experiences
workforce identity platforms
customer identity systems
mobile and modern web applications

How OIDC works at a high level

An OIDC login flow usually involves these parties:

User: the person trying to sign in
Application: the app the user wants to access
Identity Provider (IdP): the system that authenticates the user
Authorization Server: often part of the identity provider that issues tokens

A typical flow looks like this:

The user opens an application.
The application redirects the user to an identity provider.
The user authenticates with that provider.
The provider returns tokens to the application.
The application validates the tokens and signs the user in.

The key addition that makes OIDC an identity protocol is the ID token.

What is an ID token?

The ID token is a core part of OpenID Connect. It is usually a signed token that contains claims about the authenticated user.

Common claims may include:

a unique user identifier
the token issuer
the intended audience
authentication time
email address
username or profile details

The application uses the ID token to verify:

that the user really authenticated
which identity provider performed the authentication
whether the token was meant for that application

That is what separates OIDC from plain OAuth-based delegated access.

OIDC vs OAuth 2.0

This is the distinction that matters most.

OAuth 2.0 is primarily an authorization framework. It allows a user to grant an app limited access to resources without handing over a password.

OIDC extends OAuth 2.0 to add authentication features, including:

the ID token
standardized identity claims
user info retrieval
discovery and metadata endpoints
login-focused flows for applications

So if an app needs to know who the user is, OIDC is usually the right protocol layer. If it only needs delegated access to an API, OAuth may be enough.

For another common federation protocol, see /content/what-is-saml.

Where OIDC is used

OIDC is common anywhere organizations want modern login and centralized identity.

Typical use cases include:

workforce single sign-on
consumer login systems
SaaS application integration
mobile app authentication
cloud identity federation
zero trust access architectures

Because it works well with modern apps and APIs, OIDC is often preferred over older federation approaches in new deployments.

Why organizations use OIDC

Organizations adopt OIDC because it can improve both user experience and control.

Common benefits include:

centralized authentication
fewer passwords managed by individual apps
support for MFA through the identity provider
easier single sign-on across services
consistent identity claims
simpler federation with cloud services

For security teams, this can mean better visibility and more consistent enforcement of login policies across many applications.

What OIDC does not guarantee

Using OIDC does not automatically make an application secure. Security still depends on how the implementation is handled.

Important factors include:

proper token validation
secure redirect URI handling
strong MFA at the identity provider
secure session management
protection of the identity provider itself
least-privilege access to downstream systems

In other words, OIDC is a strong framework, but poor implementation can still create security problems.

Common misconceptions

“OIDC is the same as OAuth”

Not exactly. OIDC is built on OAuth 2.0, but it adds authentication and identity features. OAuth alone is mainly about authorization.

No. OIDC is used for social login, but it is also common in enterprise SSO, workforce identity, SaaS integration, and internal app authentication.

“If an app uses OIDC, it is automatically secure”

False. OIDC can be implemented well or poorly. Token validation, redirect handling, MFA, and identity provider security still matter.

“OIDC replaces every other federation protocol”

Not always. Many organizations still use SAML in some environments. OIDC is often preferred for modern apps, but the right choice depends on architecture and compatibility.

“OIDC means the app gets no user data”

No. Applications can receive identity claims and user profile information depending on scopes, consent, and configuration.

Final takeaway

OIDC is the modern standard that helps applications authenticate users through an external identity provider. If OAuth 2.0 handles delegated access, OpenID Connect adds the identity layer that makes modern login, single sign-on, and standardized authentication flows work.

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