𝗦𝗶𝗺𝗽𝗹𝗲 𝗟𝗶𝘃𝗲 𝗖𝗵𝗮𝘁 𝗔𝗹𝗺𝗼𝘀𝘁 𝗦𝗮𝗻𝗸 𝗧𝗵𝗶𝘀 𝗥𝗲𝗹𝗲𝗮𝘀𝗲

A basic live chat system almost ruined my latest release.

It sounds simple. You show nearby users and let them talk. But the technical reality is much harder. I had to connect live chat with geolocation and a rating system. This created massive complexity under the hood.

The Architecture:

• Frontend: React and TypeScript. • Backend: Node.js with Express and WebSockets. • Database: PostgreSQL for users and ratings. • Cache: Redis for active sessions and presence.

The Geolocation Problem

Matching users by location is not easy. I had to handle many edge cases:

  • Storing latitude and longitude.
  • Using Postgres extensions to query distance.
  • Handling users who deny location permissions.
  • Managing stale data when a user moves without opening the app.

If I did this again, I would separate location collection from matching into different services.

The Live Chat Reality

WebSockets bring real-time features, but they also bring chaos. I used Redis pub/sub to send messages across different servers.

The hardest parts were:

  • Cleaning up connections when users disconnect unexpectedly.
  • Preventing messages from being sent to rooms a user left.
  • Handling reconnects without creating ghost sessions.

I learned that a formal state machine is better than using simple flags.

The Rating System

Ratings seem trivial until you build them. I had to ensure:

  • Users cannot rate the same session twice.
  • Ratings aggregate quickly for profile views.
  • Data remains consistent across the app.

I used unique constraints on session IDs to prevent duplicates and cached the averages to save performance.

Lessons Learned

If I rebuild this today, I will change three things:

  1. Split matching and chat into separate modules.
  2. Use explicit modeling for WebSocket connection states.
  3. Add better logs and metrics for chat and matching from day one.

Building software is a series of small decisions. These decisions determine if your system is clean or brittle.

Have you built a live chat or a matching system? What would you do differently?

Source: https://dev.to/jaeger974/simple-live-chat-almost-sank-this-release-2pn7