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Multithreading in Compose Multiplatform Web Apps

Mon, 02 Nov 2026 00:00:00 +0000

The standard way to work with multithreading and asynchronous code in Kotlin is to use the kotlinx.coroutines library.

To make code execution easier to manage, the library provides several standard dispatchers:

Dispatchers.Main — for working on the UI thread, if the platform has one.
Dispatchers.Default — for CPU-intensive work, such as calculations and data processing. Used by default when no dispatcher is specified.
Dispatchers.IO — for blocking I/O operations, such as file operations or blocking network calls.
Dispatchers.Unconfined — starts a coroutine on the current thread until its first suspension. After that, the coroutine may resume on a thread chosen by the suspending operation.

In Compose Multiplatform apps, application code usually starts running on Dispatchers.Main. So all blocking and heavy operations need to move to other threads to avoid blocking the UI.

Profiling a Compose Multiplatform app in the browser

Wed, 07 Oct 2026 00:00:00 +0000

You’ve noticed a performance problem #

First steps #

I hope everyone already knows that to check the performance of a Compose app, you need to run it in release mode. Development mode is designed for quick iterations and skips a lot of build-time optimizations. So first of all, if you see that the app is lagging and dropping frames, make sure you’re not running it in development mode.
If the problems are still there even in a release build, then, of course, you need to figure out what went wrong. Don’t jump straight into the hardcore stuff! First, just take a sensible look at what’s happening inside the app. Nobody knows your codebase better than you do. Maybe, by accident, you’re decoding a large JSON file on the UI thread. Or maybe you’re making a database query. And so on. 😉

Offline Support for Compose Multiplatform Web Apps

Wed, 30 Sep 2026 00:00:00 +0000

The No-Internet Problem. #

Let’s assume you already have a Compose Multiplatform app that runs on the web.
Perhaps you’ve even configured a web manifest so users can install it on their device as a PWA.
Let’s make it even better and bring its behavior closer to a native app.
When a user runs an app in a browser, it’s reasonable to assume they have an internet connection. But if a user has installed a PWA app and its icon is available on the desktop, it’s reasonable to expect it to behave like a native app when there’s no internet connection.

Compose Multiplatform vs CORS

Thu, 24 Sep 2026 00:00:00 +0000

The problem #

I’m a Kotlin developer, and I really love building my own side projects in Kotlin. For the UI, I use Compose Multiplatform, of course.

On the one hand, my apps work natively on all platforms, including Android and iOS. On the other hand, publishing them in the official app stores is a huge problem. It’s expensive and requires filling out a lot of forms. And every six months to a year, both Google and Apple require you to update your apps to use new SDKs.