Chat App Multiapps.

Description

Chat App Multiapps (Chatku) is an omnichannel customer-support chat system for medium businesses running a team of 6–20 agents. Messages from many channels — WhatsApp, Telegram, Web Chat, Instagram, Facebook Messenger, LINE, Slack, and X — all land in one shared dashboard, where agents can see and reply to every conversation in real time.

Background

Medium support teams often juggle customer messages across a dozen separate apps and inboxes, which leads to missed replies and two agents answering the same person. Chatku centralizes every channel into a single inbox with real-time updates and built-in double-reply prevention, so a small team can cover many platforms without stepping on each other.

Goal

Provide one dashboard for all channels: agents reply from a single place, supervisors monitor conversations and override assignments, and admins manage users, teams, inboxes, and channel integrations — all delivered in real time and protected against double replies.

Features

• Unified inbox across Telegram, Web Chat (embeddable widget), WhatsApp (Meta Cloud API + a legacy whatsapp-web.js path), Instagram DM, Facebook Messenger, LINE, Slack, and X/Twitter — with Email on the roadmap.
• Real-time messaging over Socket.IO with live conversation updates.
• Double-reply prevention via typing indicators and an active-conversation lock backed by Redis.
• Role-based access — admin, supervisor, and agent, each with a distinct capability set.
• Multi-tenancy — multiple businesses/tenants isolated within one deployment.
• Embeddable web widget — widget.js served natively for any business website.
• Per-channel pipeline — a webhook → worker (BullMQ) → shared-helper flow so every channel behaves consistently.

Technologies

• Backend: Fastify (Node.js / TypeScript), Socket.IO, BullMQ workers, Prisma ORM over MySQL, and Redis (ioredis).
• Frontend: Next.js (App Router) dashboard.
• Infrastructure: a single-public-port design (the backend proxies the internal Next.js server), Docker Compose, and PM2 (ecosystem.config.js).

How to Run

npm install
cp .env.example .env        # configure MySQL, Redis, and channel tokens
npx prisma migrate dev
npm run dev                 # runs backend + frontend together
# open http://localhost:3000

By default the backend (:3000) is the only public port: it serves the REST API at /api, Socket.IO, channel webhooks, and widget.js, and proxies everything else to the internal Next.js server (:3001). A Docker Compose setup is also provided for a containerized run.

Technical Decisions

• Single public port. One URL and one command run the whole app — the Fastify backend serves the API, real-time layer, webhooks, and widget, and proxies the Next.js dashboard behind it.
• Channel-agnostic pipeline. Every channel follows the same webhook → BullMQ worker → shared helpers flow, so adding a platform is a new adapter rather than new architecture. A ChannelType enum models all channels uniformly.
• Real-time coordination with Redis. Presence, typing indicators, and active-conversation locks run on Redis + Socket.IO to guarantee that two agents never reply to the same conversation.
• Official vs unofficial APIs. The Meta Cloud API is the supported WhatsApp path; whatsapp-web.js is kept as an internal/legacy option only (it violates WhatsApp’s ToS and is not offered commercially).

What I Learned

• Designing a channel-agnostic message pipeline that scales to many platforms without special-casing each one.
• Coordinating real-time state (presence, typing, locks) with Redis and Socket.IO.
• Running a decoupled Fastify + Next.js application behind a single port and URL.
• Weighing the trade-offs between official and unofficial messaging APIs.

Notes

Private repository. Image and live preview will be added later. WhatsApp Web (whatsapp-web.js) is internal/legacy only and not part of any commercial offering, and the Email channel is still on the roadmap.