What is Flutter? Simply explained.
What is Flutter? Flutter is Google's open-source framework for building apps for iOS, Android, web, Windows, macOS and Linux from a single codebase. This page explains in plain language how that works and where the limits are.
Since 2017
Released by Google, stable since late 2018, open source under a BSD licence.
Six platforms
iOS, Android, web, Windows, macOS and Linux from one codebase in Dart.
Proven at scale
Google Pay, the My BMW App, eBay Motors and Nubank run on Flutter.
Flutter, clearly explained.
What is Flutter? The definition.
Flutter is an open-source UI framework by Google for cross-platform app development. Released in 2017 and stable since late 2018, it builds applications for iOS, Android, web, Windows, macOS and Linux from a single codebase. One team writes the code once and ships it everywhere.
The Flutter framework consists of widgets as ready-made building blocks for interfaces, a rendering engine that draws them itself, and tooling for development, testing and publishing.
How Flutter works.
Flutter draws its interface itself. Other frameworks remote-control the operating system's native controls; Flutter ships its own rendering engine (currently Impeller, previously Skia) and paints every button directly onto the screen. The app therefore looks the same on every device, with no translation layer slowing it down.
Release builds are compiled ahead-of-time (AOT) to native machine code, without an interpreter and without a WebView. For the web, Flutter compiles to JavaScript or WebAssembly. During development, hot reload shows every change in the running app instantly.
The Dart language.
Flutter apps are written in Dart, a type-safe language by Google with just-in-time compilation for hot reload and AOT compilation for release builds. Anyone who knows Java, C#, TypeScript or Kotlin picks up Dart quickly. In Flutter, everything is a widget: Center(child: Text('Hello world')) centres a text on the screen.
Benefits and limits of Flutter.
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One codebase, every platform
Development, testing and every later change happen once. That lowers build costs and, above all, maintenance costs.
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Native performance, the same look everywhere
AOT-compiled and self-rendered: Flutter apps feel like native apps because technically they are.
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Hot reload, a huge selection of widgets and a mature package ecosystem shorten the time to launch.
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Limits: hardware access, 3D, app size
Exotic hardware interfaces need native modules in Swift or Kotlin; high-end 3D games belong to Unity or Unreal.
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Flutter ships its engine and framework, so simple apps are a few megabytes larger than minimal native counterparts, which rarely matters in practice.
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Flutter on the web: for app-like applications
Dart compiles to JavaScript or WebAssembly. That suits dashboards, customer portals and internal tools, less so blogs and shops.
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In the browser, too, Flutter draws the interface itself without classic HTML elements and loads engine and framework on the first visit. Where search visibility and load time decide, classic web technologies are usually the better choice.
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Flutter vs. React Native vs. native
Flutter uses Dart and renders itself; React Native uses JavaScript and drives native controls. Two native apps cost twice as much to build and maintain.
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Flutter delivers an identical look on every device and more mature desktop support, React Native the platform-typical look with more special cases. Which fits depends on team and use case. Native pays off for apps whose core is the deepest system integration.
Have Flutter assessed for your project.
You have an app idea and wonder whether Flutter fits? We check that with no obligation and tell you if another technology fits better.
Flutter you can try: our own app.
Pauly · dictate your shopping list
Pauly is our voice-controlled shopping list app, built entirely with Flutter: on-device speech recognition, automatic categorisation, live sharing. Install it and see for yourself how a Flutter app feels.
Frequently asked questions about Flutter.
Is Flutter free?
Yes. Flutter is open source (BSD licence) and free to use, including commercially. Costs arise for development, operations and the app stores' developer accounts.
Can I build a Flutter app myself with AI, or do I need an agency?
For first experiments, AI and a bit of Dart curiosity go a long way. For an app that survives store review and stays maintainable, experience helps: we build every app AI-assisted, with knowledge from our own store apps.
Who owns Flutter, and is it future-proof?
Google develops and maintains Flutter; the source code is public and a large community contributes. It has been among the most widely used cross-platform frameworks for years, and BMW, eBay and Toyota run it in production.
Which well-known apps use Flutter?
Google Pay, the My BMW App, eBay Motors, Nubank, Alibaba's Xianyu and infotainment applications from Toyota. Plus Pauly, our own shopping list app in both stores.
When is Flutter the right choice?
When you want to reach several platforms with one budget, get to market fast or lower maintenance costs. Less so for pure content websites, high-end 3D games or apps whose core is the deepest platform integration.
Now you know what Flutter can do.
Whether it fits your project is something we settle in a first call.
Ask a Flutter question.
Write to us. We answer in plain language, no technical background needed.
We usually reply within 24 hours.
Remote and on site in Germany, Austria and Switzerland. International projects on request.