Convex: An Open-Source Reactive Database

Convex is changing how we build dynamic web applications. It combines the power of a reactive serverless backend with the type safety and familiarity of TypeScript. You define data models, queries, and mutations — all in .ts files — and Convex handles real-time sync, scaling, and infrastructure for you.

What sets Convex apart is its unified development experience: defining database tables, writing backend functions, and using them on the client — all with first-class TypeScript support and end-to-end reactivity.

How Convex Changes the Game

Unlike traditional SQL or NoSQL systems, Convex was built from the ground up to support fully reactive workflows. With Convex, your UI automatically updates when the data changes — no need to manually set up WebSockets or manage subscriptions. Queries and mutations are written as TypeScript functions, while Convex manages the backend logic.

Key features that make Convex stand out:

• Native TypeScript support: Backend functions and client access are fully type-safe and tightly integrated.

• Reactive queries: Frontend components automatically reflect changes in the database.

• Serverless scalability: ACID transactions, optimistic locking, and automatic performance optimization.

• Optional schema: Start with unstructured inserts, refine your types later.

This makes Convex ideal for building live-updating features — like chat apps, dashboards, collaborative editors, and more — without the extra complexity of traditional backend stacks.

Real Code, Real Simplicity

Here are simple examples showing why Convex is both powerful and easy to use:

1. A mutation to send a chat message:

// convex/chat.ts
import { mutation } from './_generated/server';
import { v } from 'convex/values';

export const sendMessage = mutation({
  args: { user: v.string(), body: v.string() },
  handler: async (ctx, args) => {
    await ctx.db.insert('messages', {
      user: args.user,
      body: args.body
    });
  }
});

2. A reactive query to get recent messages:

// convex/chat.ts
import { query } from './_generated/server';

export const getMessages = query({
  args: {},
  handler: async (ctx) => {
    const messages = await ctx.db.query('messages').order('desc').take(50);
    return messages.reverse();
  }
});

3. Type-safe schema definition with defineSchema:

// convex/schema.ts
import { defineSchema, defineTable } from 'convex/server';
import { v } from 'convex/values';

export default defineSchema({
  messages: defineTable({
    author: v.string(),
    body: v.string()
  })
});

Once a schema is defined, Convex automatically generates types. On the frontend, your query hooks will know the exact structure of the messages table — down to the type of each field.

A Four-Step Developer Workflow

Building a live-updating app with Convex takes just four steps:

1. Define your schema (optional): Use defineSchema() to add static types to your data models.

2. Write your queries and mutations: All in TypeScript — no new DSL to learn.

3. Connect the frontend: Use useQuery(), useMutation(), or Convex’s React hooks.

4. Enjoy real-time reactivity: Your UI stays in sync automatically, no subscriptions to manage.

This streamlined process replaces backend layers (API, validation, pub-sub) with a unified development model.

What You Can Build Today

Convex is a great fit for applications such as:

• Real-time chat apps and collaborative editors

• Interactive dashboards and analytics engines

• Lightweight multiplayer games or simulations

• Serverless tasks like scheduled DB operations or API integrations

With support for both cloud and local hosting, you can develop locally and scale securely in production.

Why Developers Love It

Community feedback:

Workflows and productivity are significantly faster — no context switching. Reactive features like chat or real-time interfaces are incredibly easy to implement.

In Conclusion

Convex is more than just a database. It’s a full development environment that unifies frontend and backend into a single experience with TypeScript at its core. With built-in reactivity, serverless scalability, and type safety, Convex is a compelling choice for building modern, real-time web applications.