Supabase (PostgreSQL + Auth)

Supabase is the open source Firebase alternative providing a production-ready Postgres database with integrated authentication and real-time listeners.

Supabase delivers a full-stack backend by wrapping a dedicated PostgreSQL instance with powerful tooling. It handles user management through GoTrue (supporting OAuth, magic links, and MFA) and enforces data security via Row Level Security (RLS) policies. Developers get a suite of features including an auto-generated REST API (PostgREST), real-time database subscriptions via WebSockets, and edge functions for custom logic. It is built on portable, open-source standards to eliminate vendor lock-in while scaling to millions of users.

https://supabase.com