Devise vs Guardian: What are the differences?

Devise: Flexible authentication solution for Rails with Warden. Devise is a flexible authentication solution for Rails based on Warden; Guardian: Remove the OAuth dance with one request. Avoid dealing with OAuth logic in your code, and spend more time creating your product. Guardian reduces the OAuth footprint in your code to a single request. Built with modularity in mind, Guardian leverages plugins to handle OAuth flows, should you encounter a flow that Guardian doesn't handle, create a small flow plugin to do so and carry on. Guardian comes with 5 pre-made plugins that cover 99% of OAuth services.

Devise and Guardian can be categorized as "User Management and Authentication" tools.

Devise and Guardian are both open source tools. It seems that Devise with 20K GitHub stars and 4.76K forks on GitHub has more adoption than Guardian with 628 GitHub stars and 42 GitHub forks.