Simple. Secure. Speedy.
Burgerauth is a Free and Open Source OAuth2 client, great for corporate single-sign on and cross-application authentication.
Burgerauth really does work anywhere - it doesn't even require an external internet connection. Self-host on as many intranets as you want!
Burgerauth is beyond simple. Unlike KeyCloak, which requires you to install OpenJDK, configure a database, configure providers, and so on, Burgerauth works right out of the box - all you need to do is copy the config, run the command, and Burgerauth takes care of the rest.
Burgerauth uses the Go programming language for increased stability and amazing speed. It has error handling you'll find nowhere else (sane)!
Burgerauth is designed with security in mind. It doesn't use any cross-site cookies, hacky # query strings and keeps everything in first-party isolation. Even the server doesn't get to see your encryption keys.
Burgerauth is open source, meaning you can view the source code, modify it, and even host your own instance. It's licensed under the AGPL License, so you can do whatever you want with it, as long as you share the love and keep it free!