Casbin

Casbin is worth adding because it fills a real infrastructure gap between basic auth providers and production authorization policy needs. The official site positions it as an authorization library supporting many access-control models including ACL, RBAC, ABAC, ReBAC, and more, across a wide range of languages. That makes it highly relevant for teams that already have identity solved but need a serious policy enforcement layer inside applications and services.

Its pricing story is straightforward because Casbin is open source. The official site and GitHub repository center the project as an Apache-hosted OSS authorization library, and there is no public commercial pricing grid on the project site. That means the software is free to adopt, while the practical cost sits in implementation effort, policy design, and any enterprise support or adjacent commercial tooling a team might decide to add later.