What Sets Them Apart
Supabase is an open-source Firebase alternative built on PostgreSQL, which means you get the full power of a relational database with SQL queries, joins, foreign keys, and ACID transactions. The free plan includes 500 MB database storage, 2 GB bandwidth, 50,000 monthly active users for auth, and 1 GB file storage. The Pro plan at $25/month scales to 8 GB database, 250 GB bandwidth, 100,000 MAUs, and adds daily backups and email support. Supabase provides auto-generated REST and GraphQL APIs via PostgREST and pg_graphql, real-time subscriptions via Postgres logical replication, Row Level Security for fine-grained access control, and edge functions powered by Deno.
Authentication and Database Architecture
Firebase by Google is the most mature BaaS platform, battle-tested at massive scale by apps like Duolingo and The New York Times. It uses Firestore (a NoSQL document database) and Realtime Database as its storage engines. The free Spark plan includes 1 GB Firestore storage, 10 GB bandwidth, 50,000 daily reads, and 10,000 daily auth operations. The Blaze pay-as-you-go plan charges $0.18 per 100,000 reads and $0.18 per GB stored. Firebase excels at real-time synchronization — Firestore can push updates to millions of concurrent clients with minimal latency. It also offers Cloud Messaging (push notifications), Remote Config, Crashlytics, and A/B testing — a comprehensive suite that no competitor fully matches.
Convex takes a fundamentally different approach with its reactive database engine. Instead of traditional REST or GraphQL APIs, Convex uses TypeScript functions that automatically react to data changes — when you write a query, it re-runs and pushes updates to connected clients whenever the underlying data changes. The free plan includes 1 GB storage, 2 GB bandwidth, and 25,000 function calls per day. The Pro plan at $25/month adds 16 GB storage, 16 GB bandwidth, and 500,000 daily function calls. Convex's killer feature is end-to-end type safety: your database schema, server functions, and client queries share types with zero code generation steps. The trade-off is vendor lock-in — Convex is a proprietary platform with no self-hosting option.
Pricing and Vendor Lock-in
Authentication and storage support vary across these platforms. Supabase Auth supports email/password, magic links, phone OTP, and 20+ OAuth providers including Google, GitHub, Apple, and Discord — all free regardless of plan. Firebase Auth is similarly comprehensive with support for anonymous auth, phone auth, and multi-factor authentication on the Blaze plan. Convex recently added Convex Auth but many teams still pair it with Clerk or Auth0 for production use. For file storage, Supabase offers S3-compatible object storage with a CDN, Firebase provides Cloud Storage backed by Google Cloud, and Convex includes built-in file storage with automatic URL generation.
The Bottom Line
Vendor lock-in is the most important long-term consideration. Supabase wins decisively here — it's fully open-source (MIT licensed), you can self-host the entire stack on your own infrastructure, and your data lives in standard PostgreSQL that works with any Postgres-compatible tool. Firebase data lives in Google's proprietary Firestore format, and while you can export data, migrating away requires rewriting your entire data access layer. Convex has the highest lock-in as a closed-source proprietary platform. For teams that value data sovereignty, open-source foundations, and the flexibility of SQL, Supabase is the strongest choice. Firebase remains unbeatable for apps that need its mobile SDK ecosystem and Google Cloud integration. Convex is ideal for real-time collaborative apps where its reactive model eliminates the complexity of manual cache invalidation.