Building Real-Time Systems: Chat, Notifications, and Live Updates
Real-time features feel simple to users and are surprisingly hard to build well. Here's how I build reliable chat, push notifications, and live updates — and the architecture that keeps them from falling over.
Shayan Jamil·May 24, 2026·6 min read
Real-time features are deceptive. To a user, a chat message appearing instantly or a notification popping up feels obvious and simple — "of course it works like that." Behind the scenes, making it reliable is one of the trickier things in app development. Plenty of products have real-time features that work great in a demo and then get flaky the moment they have real users.
This post is about how I build real-time features that actually hold up: live chat, push notifications, and dashboards that update as things happen. If your product needs any of these, it's worth understanding what's really involved.
What counts as "real-time"
Real-time features are the parts of an app where things happen live, without the user refreshing:
- Chat and messaging — messages appear instantly for everyone in the conversation
- Notifications — in-app alerts and push notifications that arrive as events happen
- Live updates — dashboards, feeds, or statuses that change in front of you (think live order tracking or a sales dashboard ticking up)
- Presence — knowing who's online, who's typing
These features make products feel alive and responsive. They're also where careless engineering shows up fastest.
The business problem: real-time is where "it works on my machine" goes to die
The usual story: a developer builds chat, it works perfectly when they test it with two browser tabs, everyone signs off. Then it goes live, and with more users it starts dropping messages, showing them out of order, double-sending notifications, or quietly falling apart when the server restarts.
The reason is that real-time systems have to deal with hard realities that a two-tab demo never exposes: many simultaneous connections, users on flaky mobile networks who disconnect and reconnect constantly, servers that need to restart without dropping everyone, and the need to deliver a message even when the recipient's app is closed. Building for those realities from the start is the difference between a feature that delights and one that embarrasses you.
How I build real-time features properly
WebSockets for the live connection
Normal web requests are one-and-done: the app asks, the server answers, the connection closes. Real-time needs an open, two-way channel so the server can push data to the app the instant something happens. That's what WebSockets provide (I commonly use Socket.io for this). It's the backbone of live chat and live updates.
A way to scale beyond one server
Here's a subtle but critical point. When you have more than one server (which any growing app will), a user connected to server A needs to receive a message sent through server B. Without a shared coordination layer, real-time silently breaks as you scale. I use a shared layer (commonly Redis) so messages reach the right users no matter which server they're connected to. This is the kind of thing that's invisible until it's missing.
Background queues for delivery
Sending notifications, especially push notifications to thousands of devices, shouldn't happen inside a user's request. I push this work onto background job queues (often Redis-backed) so it's reliable, retryable, and doesn't slow anything down. If a notification fails to send, it can be retried instead of silently lost.
Push notifications that actually arrive
In-app real-time only reaches users who have the app open. Push notifications (through services like Firebase Cloud Messaging) reach users when the app is closed — which is what brings them back. Getting push right across iOS and Android, with the right device-token handling and deep linking, is its own careful piece of work.
Designing for disconnection
Mobile users drop connection constantly. A good real-time system handles reconnection gracefully and makes sure a user catches up on what they missed while they were away, rather than silently losing messages.
The architecture question that matters
"What happens when you have more than one server?" If real-time was built assuming a single server, it will break the moment you scale. Designing for multiple servers from the start — with a shared coordination layer — is what separates a real system from a demo.
A realistic example
Real-time has been central to a lot of my work. On a multi-tenant SaaS platform, I built real-time chat and notifications using WebSockets (Socket.io), a Redis-backed job queue for the work that shouldn't block requests, and Firebase for push notifications — with media handled through cloud storage. On a fan-engagement and ticketing backend, real-time notifications were built on the same kind of stack: WebSockets, Redis, and push delivery.
The reason these held up is that they were designed for production realities, not the demo. The Redis layer meant messages reached users across multiple servers. The job queue meant notification sending was reliable and retryable. Push notifications meant users got pulled back in even with the app closed. None of that is visible to the person using the app — which is exactly the point. Good real-time infrastructure is felt, not seen.
Common mistakes with real-time systems
- Assuming a single server. Real-time built this way breaks as soon as you scale out.
- Doing notification delivery inside requests instead of in background jobs, making things slow and fragile.
- Ignoring reconnection. Mobile users disconnect constantly; messages missed during a drop shouldn't vanish.
- Forgetting push notifications, so the feature only reaches users who happen to have the app open.
- No idempotency, leading to duplicate messages and notifications.
- Testing only with two tabs. Real load and real networks behave nothing like a quiet demo.
How I approach real-time work
- Use WebSockets for the live channel, with a battle-tested library.
- Design for multiple servers from day one using a shared coordination layer.
- Push delivery work to background queues so it's reliable and retryable.
- Handle push notifications properly across iOS and Android.
- Plan for disconnection and catch-up so nothing is silently lost.
- Test under realistic conditions, not just two browser tabs.
Real-time features sit on top of a solid backend, so how to build a scalable backend for a SaaS product is a natural companion. And since push notifications are a big part of this, what makes a mobile app production-ready covers the mobile side in more depth.
Need reliable real-time features?
If your product needs chat, notifications, or live updates that actually hold up with real users — not just in a demo — that's exactly the kind of work I do. I build real-time systems designed for production from the start, with the architecture that keeps them reliable as you grow.
Take a look at my projects, then get in touch and tell me what you're building. I'm happy to talk through what it'll take to make it feel instant and keep it reliable.