Open source Supabase alternative

There are roughly 15-25 legitimate open-source backend-as-a-service alternatives positioning themselves against Supabase, ranging from Firebase clones to self-hosted databases with auth layers. The common failure pattern is that most alternatives nail one dimension—say, database flexibility or self-hosting—but sacrifice developer experience, documentation, or ecosystem maturity. The actual gap isn't in the technical foundation; it's in the polish layer. Developers want Supabase's speed and ergonomics without the vendor lock-in, but building that requires not just solid infrastructure but obsessive attention to onboarding, local development experience, and migration tooling from existing platforms. The real opportunity sits at the intersection of three things: a genuinely self-hostable stack, first-class local development (Docker Compose that actually works), and clear migration paths from Supabase specifically. A new entrant should focus on making the first week frictionless—if your setup takes more than 15 minutes or requires DevOps knowledge, you've already lost indie hackers and early-stage startups to Supabase inertia.