# What is OAuth?

> What is OAuth? Learn how OAuth 2.0 works, why it matters for app security, and how social login improves user experience in mobile and web apps.

Canonical: https://app369.com/glossary/what-is-oauth/

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Quick Answer

**OAuth (Open Authorization) is an industry-standard protocol that lets users grant third-party applications limited access to their accounts on another service without sharing their password. It powers "Sign in with Google," "Sign in with Apple," and similar social login buttons.**

**OAuth 2.0** is the protocol behind every “Sign in with Google,” “Sign in with Apple,” and “Continue with Facebook” button you have ever used. It lets users authenticate with a trusted provider and grant your app limited access to their profile information, without ever sharing their password with you.

## How OAuth Works

The OAuth flow involves four parties: the **user**, your **application**, the **authorization server** (e.g., Google), and the **resource server** (e.g., Google’s user profile API).

When a user taps “Sign in with Google,” your app redirects them to Google’s authorization page. The user logs in with Google and approves the permissions your app requests. Google redirects back to your app with an authorization code. Your app exchanges that code for an access token. Your app uses the access token to fetch the user’s profile from Google’s API.

At no point does your application see or store the user’s Google password.

## Why OAuth Matters

**Security.** Users do not need to create yet another password for your app. Fewer passwords mean fewer opportunities for credential theft.

**User experience.** Social login reduces sign-up friction.

**Trust.** Users trust established providers like Google and Apple with their credentials more than they trust a new app.

## OAuth vs Authentication vs Authorization

**Authentication** answers “who are you?” by verifying identity. **Authorization** answers “what can you do?” by granting permissions. OAuth is primarily an authorization protocol, though it is commonly used alongside OpenID Connect (OIDC) to handle authentication as well.

## OAuth at App369

At [App369](https://app369.com), we implement OAuth-based social login in the majority of our mobile and web apps using [Firebase Authentication](https://app369.com/glossary/what-is-firebase/), which supports Google, Apple, Facebook, Twitter, and custom providers out of the box. [Contact us](https://app369.com/contact/) to discuss authentication for your app.

## **Related Terms **

[what is api](https://app369.com/glossary/what-is-api/) [what is backend](https://app369.com/glossary/what-is-backend/) [what is firebase](https://app369.com/glossary/what-is-firebase/)

## **Related Services **

[mobile apps](https://app369.com/service/mobile-apps/) [web apps](https://app369.com/service/web-apps/)

## **Prefer a fixed price?**

Fixed scope, fixed price, paid upfront. The work happens in writing; no call needed.

- [**API Integration**$1,200Two systems connected through their APIs, with retries, logs, failure alerts and tests.](https://app369.com/fixed-price/api-integration/)
- [**Stripe Billing Fix and Setup**$950Subscriptions, webhooks, customer portal and failed payments set up or fixed, tested in Stripe test mode.](https://app369.com/fixed-price/stripe-billing-setup/)
- [**App Fix Ticket**from $450One reproducible bug in an existing mobile or web app, diagnosed and fixed.](https://app369.com/fixed-price/flutter-firebase-bug-fix/)

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