🔐 Getting to Know Keycloak, OAuth 2.0 & OpenID Connect

When building modern applications, handling user login, roles, and secure access can get tricky fast. That’s where tools like Keycloak come in, along with protocols like OAuth 2.0 and OpenID Connect (OIDC). If you’ve heard these names tossed around but aren’t 100% sure how they fit together, this post is for you.

Let’s break it all down in plain language.

🧭 What Exactly Is Keycloak?

Keycloak is an open-source Identity and Access Management tool. In simple terms—it helps apps handle logins, roles, permissions, and things like Single Sign-On (SSO), so you don’t have to reinvent the wheel.

It’s packed with features like:

  • Logging in users via email and password
  • Letting users sign in using Google, GitHub, etc.
  • Managing user groups, roles, and sessions
  • Supporting industry-standard protocols (OAuth2, OIDC, SAML)

If you want to focus on building your app and not your auth system—Keycloak can be a lifesaver.

Keycloak Core Concepts
Image Source: Red Hat Developer

🔑 A Simple Look at OAuth 2.0

OAuth 2.0 is all about authorization. Think of it like this: you’re letting another app (say, Spotify) use some of your data from a different service (like your Google account)—but without giving away your password.

It uses a token system to allow apps to ask:
“Hey, can I have permission to do X on behalf of this user?”

OAuth is everywhere—Facebook login, GitHub login, Slack integrations—all of them rely on this flow.

OAuth 2.0 Flow Diagram
Image Source: API-University

👤 OpenID Connect: Who’s Logging In?

While OAuth 2.0 tells apps what someone is allowed to do, OpenID Connect (OIDC) is built on top of OAuth 2.0 to answer who the person is.

If you’ve ever clicked a “Log in with Google” button and your name and email appeared like magic—that’s OIDC in action.

OIDC provides identity info (like name, email, profile picture) in a standardized way, and it’s often used in combo with OAuth.

OpenID Connect Authentication Flow
Image Source: Tudip Technologies

🔄 How Keycloak Uses OAuth 2.0 and OpenID Connect

What makes Keycloak powerful is that it implements both OAuth 2.0 and OpenID Connect out of the box. When a user logs into your app via Keycloak:

  • It handles authentication (via OpenID Connect)
  • It issues access tokens (via OAuth 2.0)
  • It even offers token introspection and session management

You don’t need to implement the protocols yourself—just configure clients, realms, and identity providers through Keycloak’s admin console.

Keycloak Integration Diagram
Image Source: Red Hat Developer

🚀 Why Use Keycloak + OAuth + OIDC?

Here’s why I personally love using Keycloak in modern projects:

  • ✅ One login to rule them all (SSO is a game changer)
  • ✅ Secure by default (tokens > passwords)
  • ✅ Standardized protocols (OAuth2, OIDC, SAML)
  • ✅ Works with LDAP, Google, GitHub, Microsoft, etc.
  • ✅ Admin UI is pretty easy to use
  • ✅ Open source and actively maintained

For teams working on microservices, mobile apps, or SPAs, this combo can simplify a lot of the complexity around identity.

🛠️ Want to Try It Out?

Getting started with Keycloak is surprisingly straightforward. Here’s a quick roadmap:

  1. Download and run Keycloak (they offer a Docker image, too)
  2. Create a realm – kind of like a workspace for your apps and users
  3. Register a client app – your frontend or backend app
  4. Define user roles and permissions
  5. Test the login flow using OAuth 2.0 / OIDC
  6. Optionally connect to Google, GitHub, or LDAP

For a hands-on walkthrough, I recommend checking out this Medium article on Spring Boot & Keycloak.

🎯 Wrapping Up

If you’re building anything with user login, you should absolutely consider Keycloak and these standard protocols. They’ll save you time, boost security, and let you scale user management without stress.