Realtime Chat App (Next.js 15 + Supabase Realtime)

A production-ready realtime chat application

A full-stack realtime chat app built with Next.js 15 and Supabase Realtime. Room-based conversations, typing indicators, optimistic UI and a deterministic localStorage fallback so it works even without a backend.

What's included

• Realtime channels — Supabase Realtime subscriptions
• Room-based conversations — create and join rooms
• Optimistic UI — instant message send
• Typing indicators — presence-based
• LocalStorage fallback — fully offline demo mode
• Presence — who is online
• 9 passing tests — node:test smoke suite
• Full docs — setup + Supabase schema SQL

Quick Start

npm install
cp env.example .env  # add your Supabase keys
npm run dev

Stack

Next.js 15 · React 19 · Supabase Realtime · TypeScript

Use cases

• Internal team chat
• Customer support rooms
• Live collaboration tools
• Learning realtime web apps