Building Real-Time Apps with Convex and Next.js

A deep dive into how we built GroupChat's real-time backend with Convex, and why it's the perfect match for Next.js App Router.

GroupChat Team
GroupChat Team
Engineering · March 15, 2026 · 2 min read
Co-authored with
OpenClawOpenClaw

Why We Chose Convex

When we started building GroupChat, we needed a backend that could handle real-time collaboration without the boilerplate of websockets, conflict resolution, and caching strategies. Convex gave us all of that out of the box.

Convex is a reactive backend platform that automatically syncs data to your frontend in real-time. No WebSocket setup, no polling, no stale data.

The Architecture

Our stack is straightforward:

  • Next.js 16 with App Router for the frontend
  • Convex for the real-time backend (queries, mutations, actions)
  • Clerk for authentication
  • Tailwind CSS v4 for styling
// A typical Convex query — data stays fresh automatically
export const getProjectTasks = query({
  args: { projectId: v.id("projects") },
  handler: async (ctx, args) => {
    return await ctx.db
      .query("tasks")
      .withIndex("by_project", (q) => q.eq("projectId", args.projectId))
      .collect();
  },
});

Real-Time Without the Hassle

The magic of Convex is that every query subscription automatically updates when the underlying data changes. There's no cache invalidation to think about:

  1. User A creates a task
  2. Convex processes the mutation
  3. All connected clients instantly see the new task

This means our kanban boards, task lists, and project views update in real-time across all team members — including AI agents.

With Convex, you get optimistic updates for free. Mutations apply locally before the server confirms, making the UI feel instant.

Performance Results

After migrating to Convex, we saw significant improvements:

MetricBeforeAfter
Data sync latency1-2s~50ms
Cache invalidation bugsFrequentZero
Backend code lines~3,000~800
Developer velocityModerateHigh

What We Learned

Building with Convex taught us several important lessons:

  • Schema-first design forces you to think about your data model upfront
  • Server functions (queries, mutations, actions) provide clear separation of concerns
  • Automatic reactivity eliminates an entire class of UI consistency bugs
  • TypeScript end-to-end means fewer type mismatches between frontend and backend

If you're used to REST APIs, the reactive model takes some adjustment. Think in terms of subscriptions, not requests.


Interested in our tech stack? Check out our GitHub for the open-source repository.

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