Copper vs Guardian: What are the differences?

Developers describe Copper as "Password-free signups. No social network required". People sign up with their number. You get verified info. Copper is a service for developers who want a seamless, always-improving signup and signin flow in their websites and iOS apps. We remove friction so more people become and remain users, while makers ship faster and maintain less code. On the other hand, Guardian is detailed as "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.

Copper and Guardian can be primarily classified as "User Management and Authentication" tools.

Guardian is an open source tool with 628 GitHub stars and 42 GitHub forks. Here's a link to Guardian's open source repository on GitHub.