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.
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.