---
title: "What is the difference between OAuth and OpenID Connect?"  
description: "What is the difference between OAuth and OpenID Connect?"  
author: "ICSM Computer"  
published: 2025-06-08  
updated: 2025-06-08  
canonical: https://www.mindstick.com/interview/34215/what-is-the-difference-between-oauth-and-openid-connect  
category: "c#"  
tags: ["c#", "authentication"]  
reading_time: 4 minutes  

---

# What is the difference between OAuth and OpenID Connect?

The difference between **OAuth 2.0** and **OpenID Connect (OIDC)** lies in **purpose**:

| Protocol | Purpose | Use Case |
| --- | --- | --- |
| **OAuth 2.0** | **Authorization** (access control) | "Can this app access my data?" |
| **OpenID Connect** | **Authentication** (user identity) | "Who is this user?" |

## OAuth 2.0: Authorization Framework

- **Goal**: Allow a third-party app to **access a resource** on behalf of a user.
- **Does NOT identify** who the user is.
- **Returns**: Access Token (for accessing APIs).
- **Use Case**: Grant app access to your Google Drive files **without sharing password**.

### Example:

A fitness app wants access to your Fitbit data (but doesn't need your email or who you are).

## OpenID Connect (OIDC): Identity Layer on Top of OAuth 2.0

- **Built on top of OAuth 2.0**.
- Adds **authentication** capabilities.
- **Returns**: ID Token (JWT format), plus access token.
- **Use Case**: Let users **log in** to your app with Google, Microsoft, etc.

### Example:

Your app lets users log in with their Google account → you get **who the user is** (email, name, etc.).

## Technical Differences

| Feature | OAuth 2.0 | OpenID Connect |
| --- | --- | --- |
| **Primary Purpose** | Authorization | Authentication + Authorization |
| **Token Types** | Access Token | Access Token + ID Token (JWT) |
| **User Info** | Not provided | Provided via `userinfo` endpoint |
| **Standard Login Flow** | Not defined | Well-defined login process |
| **Token Validation** | App-defined | JWT signature validation supported |
| **Scopes** | e.g., `read`, `write` | Includes `openid`, `profile`, `email` |

## Example: Login with Google

If you just use **OAuth 2.0**, you'll get an access token for calling APIs (e.g., Google Calendar API), but **you won't know who the user is**.

If you use **OpenID Connect**, you'll also get:

- `id_token`: contains user identity info (email, sub, name, etc.)
- Access to a **userinfo endpoint** for more user claims

## Summary

- Use **OAuth 2.0** if you only need to **authorize access to APIs**.
- Use **OpenID Connect** if you want to **log in users and get their identity**.

## Answers

### Answer by ICSM Computer

The difference between **OAuth 2.0** and **OpenID Connect (OIDC)** lies in **purpose**:

| Protocol | Purpose | Use Case |
| --- | --- | --- |
| **OAuth 2.0** | **Authorization** (access control) | "Can this app access my data?" |
| **OpenID Connect** | **Authentication** (user identity) | "Who is this user?" |

## OAuth 2.0: Authorization Framework

- **Goal**: Allow a third-party app to **access a resource** on behalf of a user.
- **Does NOT identify** who the user is.
- **Returns**: Access Token (for accessing APIs).
- **Use Case**: Grant app access to your Google Drive files **without sharing password**.

### Example:

A fitness app wants access to your Fitbit data (but doesn't need your email or who you are).

## OpenID Connect (OIDC): Identity Layer on Top of OAuth 2.0

- **Built on top of OAuth 2.0**.
- Adds **authentication** capabilities.
- **Returns**: ID Token (JWT format), plus access token.
- **Use Case**: Let users **log in** to your app with Google, Microsoft, etc.

### Example:

Your app lets users log in with their Google account → you get **who the user is** (email, name, etc.).

## Technical Differences

| Feature | OAuth 2.0 | OpenID Connect |
| --- | --- | --- |
| **Primary Purpose** | Authorization | Authentication + Authorization |
| **Token Types** | Access Token | Access Token + ID Token (JWT) |
| **User Info** | Not provided | Provided via `userinfo` endpoint |
| **Standard Login Flow** | Not defined | Well-defined login process |
| **Token Validation** | App-defined | JWT signature validation supported |
| **Scopes** | e.g., `read`, `write` | Includes `openid`, `profile`, `email` |

## Example: Login with Google

If you just use **OAuth 2.0**, you'll get an access token for calling APIs (e.g., Google Calendar API), but **you won't know who the user is**.

If you use **OpenID Connect**, you'll also get:

- `id_token`: contains user identity info (email, sub, name, etc.)
- Access to a **userinfo endpoint** for more user claims

## Summary

- Use **OAuth 2.0** if you only need to **authorize access to APIs**.
- Use **OpenID Connect** if you want to **log in users and get their identity**.


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Original Source: https://www.mindstick.com/interview/34215/what-is-the-difference-between-oauth-and-openid-connect

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