What is Keycloak?

Keycloak is a free, open-source tool that helps websites and apps manage who can log in and what they can do. It lets users sign in once and then access many different services without having to log in again each time.

Let's break it down

  • Free, open-source: No cost to use, and anyone can look at or change the code.
  • Tool: A piece of software you install on a server.
  • Manage who can log in: It stores user names, passwords, and other login details.
  • What they can do: It decides which parts of an app a user is allowed to see or use.
  • Sign in once: Called “single sign-on” - after the first login, the user is automatically accepted by other connected apps.
  • Many services: Works with websites, mobile apps, APIs, and more.

Why does it matter?

Because it saves developers from building their own login system from scratch, improves security by using proven standards, and gives users a smoother experience by reducing the number of passwords they need to remember.

Where is it used?

  • A company’s internal portal where employees access email, HR tools, and project management apps with one login.
  • A SaaS platform that lets customers sign in using Google, Facebook, or a corporate account.
  • A mobile banking app that needs strong authentication and role-based access to different features.
  • An API gateway that checks each request’s token before allowing access to backend services.

Good things about it

  • No licensing fees and a large community that contributes improvements.
  • Supports industry standards like OAuth 2.0, OpenID Connect, and SAML, making integration easier.
  • User-friendly web console for managing users, roles, and settings without coding.
  • Extensible: you can add custom login pages, identity providers, or business rules.
  • Built-in support for social logins and multi-factor authentication.

Not-so-good things

  • Initial installation and configuration can be complex, especially for large organizations.
  • The admin UI feels dated and can be confusing for beginners.
  • Scaling to thousands of concurrent users may require careful tuning and extra infrastructure.
  • Advanced customizations often need Java programming knowledge, which not all teams have.