I've been looking for a low cost or self-hosted authentication system for some projects I'll be working on. Recently, I came across Appwrite. It's an open source backend server for web, mobile, and Flutter developers.
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Appwrite includes authentication with email address and password along with many of the major social oAuth providers. Appwrite also includes an entire API for data storage and file storage.
Here's a brief overview of setting up Appwrite and authenticating with email address and password in a simple React Native app.
P.S. The Appwrite team is actually working on a React Native SDK 💥!
So far, I'm really impressed with the project and the team. Over the next few weeks, I'm going to be evaluating Appwrite some more to make sure it suits my needs. As I go, I'll try to create some more demo videos.