Deep Architectural Differences: Why Cost Models Diverge
The fundamental difference between Convex and Supabase is state management architecture. Supabase exposes a full instance of PostgreSQL, providing rock-solid ACID guarantees, Row Level Security (RLS), and the immense ecosystem of Postgres extensions (PostGIS, pgvector, timescaledb). However, PostgreSQL was originally designed as a connection-oriented client-server database. When 10,000 web clients open direct connections or listen to WAL replication streams, server memory spikes rapidly unless managed behind a pooler like Supavisor.
In contrast, Convex functions as a deterministic distributed state machine written from the ground up for TypeScript web applications. Queries are evaluated and cached based on their exact input arguments and dependent document IDs. When 5,000 users look at the same live chat thread, Convex serves them from an in-memory replica edge without querying the database 5,000 separate times.
Feature & Cost Breakdown (2026)
| Metric / Dimension | Convex Backend | Supabase (Postgres) |
|---|---|---|
| Base Plan Price | $50/mo baseline + $25/seat | $25/mo flat per project |
| Database Engine | Custom Document Store (TypeScript) | PostgreSQL 15 / 16 |
| Realtime Sync Engine | Automatic query dependency caching | Elixir Phoenix Channels (WAL broadcast) |
| Included Storage | 50 GB document, 50 GB files | 8 GB database disk, 100 GB storage |
| Disk Storage Overages | $0.25 / GB / mo | $0.125 / GB / mo (Ratcheted) |
| Edge Functions | Native Convex Mutations & Actions | Deno Edge Functions (2M free, $2/1M over) |
| Team Collaboration | Billed per seat ($25/user) | Unlimited team seats on Pro |
| Self-Hostable? | Open-source local backend available | 100% open-source Docker compose stack |
When to Pick Convex vs Supabase
Choose Convex if:
- You are building a React/Next.js/React Native application with heavy live synchronization (collaborative whiteboards, multiplayer games, realtime messaging, live document editors).
- You want full end-to-end TypeScript type safety without generating Prisma, Drizzle, or Supabase client types manually.
- You want to eliminate connection pooling, WAL replication configuration, and database connection limits entirely.
Choose Supabase if:
- You require complex relational queries, multi-table joins, window functions, and analytics that document stores struggle to represent cleanly.
- You have existing SQL tooling, BI tools (Metabase, Tableau), or data pipelines connecting directly via standard PostgreSQL drivers.
- You have a multi-developer engineering team where paying $25/seat would inflate your backend budget compared to Supabase's fixed $25 project rate.