Convex — Reactive Backend and Database for Apps

Introduction

Convex provides a reactive backend where database queries, serverless functions, and real-time subscriptions are defined together in TypeScript. Changes to data automatically propagate to all connected clients without manual WebSocket management or polling.

What Convex Does

• Stores data in a transactional document database with strong consistency
• Runs server-side TypeScript functions with automatic caching and reactivity
• Pushes real-time updates to connected clients when query results change
• Provides built-in file storage, authentication, and scheduled jobs
• Offers a fully self-hostable open-source backend since the 2024 release

Architecture Overview

Convex is built in Rust and uses a custom transactional document store as its storage layer. Server functions are defined in TypeScript and executed in a V8 isolate runtime. The reactivity system tracks which documents each query reads and automatically re-runs queries when those documents change, pushing updates to subscribed clients over WebSockets.

Self-Hosting & Configuration

• Bootstrap a new project with the create-convex CLI in seconds
• Self-host using the open-source convex-backend Docker image
• Define your schema, queries, mutations, and actions in a convex/ directory
• Environment variables and secrets are managed through the dashboard or CLI
• Deploy to production with zero-downtime schema migrations

Key Features

• Automatic reactivity eliminates manual cache invalidation and data refetching
• ACID transactions across multiple documents and tables
• TypeScript end-to-end with generated types from your schema
• Built-in vector search for AI embedding queries
• Scheduled functions and cron jobs without external task queues

Comparison with Similar Tools

• Supabase — Postgres-based with REST APIs and real-time via Change Data Capture, but not reactively re-executing queries
• Firebase — Google-managed NoSQL with real-time sync, but proprietary and limited query capabilities
• PocketBase — Lightweight Go backend with SQLite, simpler but no reactive query system
• SpacetimeDB — Unified DB and server with WASM modules, focused on game workloads
• Hasura — GraphQL layer over Postgres with subscriptions, but requires managing the underlying database

FAQ

Q: Is Convex fully open source? A: Yes, the Convex backend was open-sourced in 2024 under the FSL (Functional Source License), which converts to Apache 2.0 after two years.

Q: Can I self-host Convex? A: Yes. The open-source backend can be deployed on your own infrastructure using Docker.

Q: What client frameworks does Convex support? A: Official React, Next.js, and React Native clients are available. Community clients exist for Vue, Svelte, and plain JavaScript.

Q: How does Convex handle file uploads? A: Convex includes built-in file storage with automatic URL generation. Files are stored alongside your data with no external S3 configuration required.

Sources

• https://github.com/get-convex/convex-backend
• https://docs.convex.dev