What is Flutter?

Flutter is a cross-platform framework that enables building applications for mobile devices (iOS and Android), desktop (Mac and PC), and web browsers from the same codebase, shortening the app development process and giving significant savings in the Total Cost of Ownership for the Product Owners.

Flutter has been used for over one million iOS and Android apps (data from May 2023). Flutter is also an open-source mobile UI framework written using C, C++, a programming language called Dart, and Skia Graphics Engine, developed by Google and released in beta in May 2017 (the first stable version was released in December 2018). 

Flutter is used to build cross-platform apps, which means iOS and Android applications built with Flutter use a single codebase, compile directly to the ARM native code, and access the platform APIs and services without any communication bridge. With Flutter, you can create well-performing, user-friendly, and beautiful apps in no time. We believe Flutter offers even better solutions than React Native (which also can be used for mobile app development).

The current state of Flutter technology

The Flutter framework has its core components being developed by the Google team, which is a plus for its further development and stability. Even tho Flutter is still a new technology; it's a fully stable solution. Google team takes care of its stable support and is transparent about the development roadmap, planning at least one year ahead and considering developers' opinions while making fixes and improvements. 

Moreover, Flutter supports building apps on a wide variety of devices and form factors, including web, and mobile platforms (iOS and Android), and desktop (Windows, macOS, Linux); living rooms (TV, Stadia); smart displays (Assistant); and beyond (cars, embedded devices, and appliances).

Flutter helps its users create the best experiences for their applications with its fast, productive, open, and pervasive toolkit. It also allows for the implementation of solutions necessary for accessibility support. It is also constantly developing - the Google Flutter team announces changes regarding the development of Flutter on average 3-4 times a year.

The major change in the Flutter 2.0 version was to confirm the sound null safety, which is mathematical proof that no object references will have null or void values. Flutter 2.10 covered a wide range of improvements, including updates across Android and iOS and the web. Another significant change was allowing the production of Windows apps on the stable channel of Flutter by default.

Flutter 3.3 version came along with Dart 2.18.1 and brought some exciting widgets, features, DevTools, and useful VSCode extensions that can improve app development. Google is also working on increasing its supply chain security and bringing the infrastructure in line with the requirements described in SLSA documentation. They have achieved Supply Chain Levels for Software Artifacts (SLSA) Level 2 security.

Besides that, the broad developer community is an additional source of market credibility for the product. Since Flutter's early days, it has been attracting developers who emphasize the ease and speed of Flutter app development (as a result of Flutter's architecture), even with a demanding user interface (visual components) and complex animations. Plus, it's a multi-platform solution (for iOS and Android apps).

Flutter App Development

LeanCode is an Expert in Flutter

At LeanCode, we gather 25+ skilled Flutter Developers who help our clients build well-performing applications with great UI and UX experience on the highest level (similar to native performance).  We can ensure that the Flutter framework provides an excellent opportunity to deliver mobile applications much faster than the other cross platform development solutions.

Why do we call ourselves experts in Flutter?

Flutter is our core mobile technology

We think the Flutter framework is a great solution for mobile applications, and that’s why we fully focus on this technology. We have been developing mobile apps in Flutter since 2018, and we deliver several Flutter mobile apps for our clients every year. It allowed us to develop the skills of our Flutter team to a very great extent, and you can take advantage of it while working with us. If you have chosen Flutter already, you can be sure that LeanCode is a top Flutter company.

We are the official Flutter consultancy firm

LeanCode is an official Flutter consultancy company. We are among the top global Flutter firms listed on the official Flutter.dev page. We are thankful to Google's FlutterDev team for the recognition. This inspires us to keep sharing Flutter knowledge and crafting top-notch Flutter applications for our clients.

We gather 25+ Flutter Developers

A large Flutter team gives more possibilities - from developing smaller Flutter applications to those dedicated to enterprises in the creation of which a dozen or so Flutter Developers are involved. Besides that, our Flutter team members have already moved from general skills to specialization in specific solutions such as Bluetooth technology, payments integrations (Stripe, Google Pay, Apple Pay) design systems, media services, etc.

We have a CoreLibrary for Flutter

We have a LeanCode CoreLibrary for building mobile apps in Flutter. This library contains Flutter packages created by us, such as user authentication, Flutter communication with the backend services, or chat. We also have experience developing and maintaining component libraries within a design system.

We create our Flutter packages

Our Flutter and Dart packages simplify and speed up the work of our team by reducing the need to write additional code and reducing the number of bugs that could arise. The fact that specific solutions have already been tested and are compliant with security standards (for Android apps and iOS apps) increases the application's stability.

We are involved in the Flutter Community

We are a part of the Flutter Community. LeanCode engages in organizing the Flutter Warsaw Event (the biggest European Meetup dedicated to Flutter with 1.8K+ members). There were 17+ editions already. We also organized the Flutter Europe Conference. Our Flutter Developers share their knowledge by supporting open-source projects and giving speeches at tech conferences both in Poland and abroad.

We teach good Flutter practices

We are in constant cooperation with the Warsaw University of Technology, where we teach Flutter theory and practice. We also take part in other educational events dedicated to future developers. We also run the LeanCode Internship, where students and graduates have the opportunity to work on an actual mobile application project and learn Flutter best practices by working in a real project team.

We develop the Flutter UI testing framework

LeanCode is developing Patrol – a Flutter-first UI testing framework that revolutionizes the way we test our Flutter apps. We use it internally, but it's also an open-source project gaining new users each month. Patrol can drive your Flutter app in a way that no other tool ever could. It can interact with the operating system UI, open the notification shade, and toggle Wi-Fi and Location so that you can test truly real-world scenarios. Patrol is made for automated testing of the app's UI.

We build Flutter enterprise apps

LeanCode is known for delivering enterprise Flutter applications. One of them is a mobile Flutter application for Credit Agricole Bank Polska, a Polish branch of Crédit Agricole Group. Its mobile banking application is dedicated to retail clients. You can read the Case Study of this app, written from a technical perspective. Our clients can benefit from our extensive experience.

We have conference speakers and GDE on board

Our Head of Mobile is an official Google Developer Expert in Flutter & Dart. Our team members also take part in global Flutter conferences and meetups. As an example, they have given 11 talks in 2023. Our clients can be sure that the knowledge about building Flutter applications within the team is very high, and we are happy to share it with the Flutter community and our clients.
Meet our expert

Let's schedule a 20 minute talk

Łukasz Kosman, CEO LeanCode

This is the initial scoping call. Its purpose is to get a better understanding of what you want to build. After this call, you will have an idea about your project's feasibility and the ballpark estimates.

Łukasz KosmanCEO at LeanCode
Flutter recognition

Even big companies use Flutter framework

The number of applications built in Flutter is growing. Even such companies as Credit Agricole Bank Polska, Société Générale, Toyota, Moia (VW Group), the MediaMarktSaturn Retail Group, and Sonos decided to take advantage of this framework. Nowadays, it also become a popular solution for such complex projects as mobile banking apps.

What are the advantages of using Flutter?


Declarative UI

Flutter does its own UI drawing, which frees us from being dependent on the operating system version. Also, the declarative style of Flutter’s UI programming means you describe only once what the UI should look like for any given state.


Effective Dart language

Flutter uses Dart programming language. It is also a client-optimized language for developing fast apps on any platform, mainly because the same Dart scripts without modification work in iOS and Android native apps without modification.


Many open-source libraries

Flutter is an open-source project with contributions from many companies and individuals worldwide and from Google. The availability of many open-source libraries shortens the time of Flutter app development.


Great documentation and community

Flutter has an engaged community that impacts the improvements and the ease of use. So when developers come across issues with code, they can look at Flutter's well-written documentation with many detailed and interactive examples of basic use cases.


Single codebase

Flutter is a set of software development tools and a cross-platform solution that allows it to build web, mobile, and desktop applications from a single codebase. It significantly increases the speed of application development.


Hot reload

Hot reload allows a developer to edit code and apply those changes immediately. Flutter has a hot reload feature, so when a change to the code appears, it can be seen instantly in the application, which positively impacts development.

How can our clients benefit from Flutter?

High Flutter app performance

Flutter aims to provide 60 frames per second (fps) performance or 120 fps performance on devices capable of 120Hz updates. Even though it is a cross-platform framework, it matches the performance of native apps.


The cost of building an app often depends on the number of operating systems where it should be available. When you take this into account, developing applications in Flutter is cost-effective since developers use the same code twice.

Less testing

Again, the fewer versions of code are required, the less testing is needed. A development team doesn’t need to write several tests for each platform which accelerates and simplifies the release process.

Easy integration

Flutter can be integrated into existing applications piecemeal as a library or module. It means you don’t always need to rewrite all of your existing app’s code to Flutter. You can integrate Flutter and take the benefits of cross-platform development even if you have previously developed a native code.

Explore our know-how

Flutter for Enterprise - ebook cover

Flutter for Enterprise

Based on the experience from large-scale projects with more than 20 Flutter Devs, we summarized best practices for building enterprise applications in Flutter.
Building Mobile Banking Apps with Flutter - ebook cover

Building Mobile Banking Apps with Flutter

This ebook is packed with technical and organizational details about delivering the "CA24 Mobile" banking application with Flutter.

Flutter is suitable not only for mobile app development

The Flutter framework was created with the intention of primarily supporting the development of mobile applications. However, the development of web rendering technologies like HTML, CSS, JavaScript, and Flutter's capabilities (Flutter 3.0 release) has also become suitable for web app development. It is also still developing to support different platforms.

Using Flutter, the existing code can be easily compiled into a client experience, embedded into the browser, and then deployed to any web server. Flutter offers support for Desktop devices, meaning mobile applications can be scaled to Windows, Linux, and macOS without needing to rewrite code. You can create beautiful apps with less effort.

Although Flutter is in a unique position of being able to target web apps designed for this new web generation, and there are also great achievements in Flutter development for desktop applications, we need to admit it may not be as effective as technologies and frameworks dedicated strictly to them. So, each case of building web applications in Flutter needs to be considered separately.

You can also count on our experience and advice in Flutter for web and Flutter for desktop.

More Flutter content

The List of Enterprise Companies Using Flutter 2023

We've curated a list of companies leveraging Flutter for mobile app development. We hope this list of Flutter enterprise apps will inspire your company to consider Flutter as a beneficial and safe solution.
The list of Enterprise Flutter apps

How We 10x Improved Flutter UI Testing With Patrol 2.0

Discover the potential of Flutter UI testing and the enhancements brought by Patrol 2.0. Find out how our dev team achieved a remarkable 10x improvement in the efficiency and reliability o UI tests, unleashing streamlined testing workflows. Dive into the article and improve your Flutter UI testing process.
Patrol UI Testing Framework by LeanCode

Flutter Pros and Cons 2023 - Summary and Recommendations

Flutter is loved by many for its simple and fast development of high-quality cross-platform apps. Let’s take a closer look if Flutter is a suitable solution in every case, i.e., when developing mobile, web, and desktop applications.
Is Flutter good for app development?