Supabase assembles a backend around vanilla Postgres: authentication, row-level security, file storage, realtime subscriptions, vector search and edge functions, all addressable through auto-generated APIs. Because the core is standard SQL, you can start on the free tier and never feel locked in.
It suits developers who want Firebase-style velocity without giving up a relational database. Teams with heavy offline-sync mobile needs may still prefer Firebase; everyone else gets portability Firebase never offered.