Flutter is a free, open-source technology developed by Google that lets you write an app for iOS, Android, the web and desktop from a single codebase. It used to be necessary to write a separate app for each platform; cross-platform tools such as Flutter release the same code to both stores. For a business, this means a shorter timeline and lower costs.
Key takeaways:
- Flutter is a Google product; apps are written in the Dart language, and one codebase produces both the iOS and the Android app.
- Its main rival is React Native, developed by Meta; both are enough for most business apps.
- A native app is written separately for each platform: the highest capability, but two codebases and a bigger budget.
- The choice of technology is a decision the user does not see but that affects the budget, the timeline and future support.
- For the client commissioning the app, what matters more than the name of the technology is the team's experience and who owns the code.
What is Flutter?
Flutter is a framework for writing the interface and logic of mobile apps in a single codebase. Google develops it and distributes it for free; its first stable version came out in December 2018 (Google Developers Blog). Flutter apps are written in the Dart programming language, which Google also created.
"A single codebase" means that the developer writes a screen once and gets both an iPhone app and an Android app from it. A web version and Windows, macOS and Linux programs can also be built from the same code.
Flutter's official showcase page lists Google apps such as Google Pay, Google Ads and Google Classroom, as well as companies such as BMW, Toyota, eBay, Nubank and Wolt (Flutter).
We explain what a mobile app itself is and what parts it consists of in the article what is a mobile app.
How does Flutter work?
Flutter draws the screen itself. In an ordinary (native) app the phone's operating system displays the buttons and lists; Flutter draws every pixel with its own rendering engine. This has two consequences: the app looks the same on iPhone and on Android, and the designer is not limited to the platform's standard elements.
Flutter's three key concepts:
- Widget. Everything on the screen is assembled from small parts: a button, text, an image, a list. These are called widgets, and the screen is built from them like Lego.
- Hot reload. The developer changes the code and sees the result on screen within a second or two. This speeds up the work.
- Compilation. The finished app is converted into code the phone's processor understands, which is why it runs fast.
The user does not notice that the app is written in Flutter: they download it from the App Store or Google Play like any ordinary app.
Who is a Flutter developer?
A Flutter developer is a developer who writes mobile apps with Flutter and the Dart language. They turn the screens prepared by the designer into code, connect the app to the server, test it and upload it to the stores.
The point the client needs to know is this: a Flutter developer writes the part of the app that sits on the phone. The back end (server), the admin panel and the design are separate jobs and often require separate specialists. The promise that "one Flutter developer will do everything" is possible on small projects but risky on complex ones.
Native, cross-platform and hybrid apps: what is the difference?
| Approach | How it is built | Technologies | Advantage | Limitation |
|---|---|---|---|---|
| Native | Separate code for each platform | Swift for iOS, Kotlin for Android | Highest speed, first access to new features | Two codebases, two teams, a longer timeline |
| Cross-platform | One codebase, two platforms | Flutter, React Native | Lower cost, simultaneous release | Extra native work for very specific features |
| Hybrid | A website is placed in an app "shell" | Capacitor and similar tools | Cheapest, built by a web team | Weaker speed and feel, risk of being rejected by the store |
Be careful with the hybrid approach: simply "wrapping" a website in an app can be grounds for rejection under the App Store rules, because an app must offer functionality and an interface that differ from the website.
Flutter vs React Native: what is the difference?
Flutter and React Native do the same job in different ways: both produce an app for two platforms from one codebase.
| Criterion | Flutter | React Native |
|---|---|---|
| Who develops it | Meta | |
| Programming language | Dart | JavaScript or TypeScript |
| How the interface is drawn | With its own rendering engine | With the platform's own (native) elements |
| Look | The same on every platform | Close to each platform's own style |
| For a web team | A new language has to be learned | A familiar language for web developers |
| Ready-made libraries | Broad, with many official packages | Very broad, the JavaScript ecosystem |
| Strongest point | A custom, animated interface | Compatibility with an existing web team and code |
In popularity they are very close: in the most recent Stack Overflow survey (2024) that lists both technologies together, 9.4% of developers said they use Flutter and 8.4% React Native (Stack Overflow). React Native's official showcase page, meanwhile, lists the apps of Facebook, Instagram, Microsoft Outlook and Teams, Amazon Shopping and Shopify (React Native).
In practice, for the client the difference lies not in the technology but in the team. A good Flutter team will write a better app than a weak React Native team, and vice versa. So before asking "which is better?", ask this: "does the team have a live app in the store built with this technology?"
What are the advantages and limitations of Flutter?
Advantages:
- One codebase, two platforms. A change is written once and tested once.
- The same look. The app looks the way the designer drew it on both platforms.
- Fast development. Hot reload and ready-made widgets help get the first version out quickly; that is why Flutter is often chosen for an MVP.
- Strong support. Google stands behind it, and the documentation is extensive.
- Expansion. A web and desktop version can also be produced from the same code.
Limitations:
- App size. A Flutter app carries all the code it needs to run, including the rendering engine (Flutter), so the file is usually somewhat larger than a native app.
- New platform features. When Apple or Google releases a new capability, native apps get to it first.
- Very specific device features. In some cases an extra module has to be written in native code.
- The talent market. Dart is not as widespread as JavaScript; if you need to change the team, the number of candidates may be smaller.
When should you choose a native app?
The native approach is chosen when the app's value depends on the phone's deep capabilities:
- heavy graphics and games;
- augmented reality (AR), complex camera and video processing;
- close work with a smartwatch, a car display or home screen widgets;
- features that run constantly in the background;
- apps intended for just one platform, which must be perfect there.
There is also a middle way: JetBrains' Kotlin Multiplatform technology makes it possible to share an app's logic across platforms, and it has been considered stable since November 2023 (JetBrains).
Most banking, shop, booking, delivery and loyalty apps do not fall into this list and are comfortably built cross-platform.
How do you choose a technology for your business?
The team, not the client, proposes the technology, but understanding the decision is your job. Depending on the situation, the usual choice is as follows:
| Situation | Usually suitable choice | Why |
|---|---|---|
| Testing an idea quickly (MVP) | Cross-platform | One codebase reaches both stores quickly |
| Shop, booking, loyalty, personal account | Cross-platform | Standard features exist in both technologies |
| The company has web developers | React Native | The team works in a familiar language |
| Custom design and animation come first | Flutter | Full control over the look |
| Games, AR, complex device features | Native | Maximum speed and capability |
| A simple catalogue or personal account, being in the store is not important | PWA | Cheapest, no download required |
When comparing proposals, ask these questions before looking at the name of the technology:
- Do you have a live app in the store built with this technology? Ask for the link, download it and check.
- Are the back end (server) and the admin panel included in the proposal?
- In whose name will the source code and the developer accounts be? Both must belong to the client.
- When iOS and Android release a new version, who will update the app and on what terms?
- Will another team be able to continue the project? Documentation and handover of the code must be written into the contract.
We show how to test a hypothesis with a small version in the article what is an MVP, and the options built without writing code in the article creating a mobile app.
How does technology affect the price of an app?
Technology affects the price in two places: initial development and later support. Two native apps mean two codebases: every feature is written twice, tested twice and every update is released twice. In cross-platform, most of this work is done once.
But technology is only one part of the price. The bulk of the budget is made up not by screens but by the server, roles, integrations and the admin panel; and these do not depend on the choice of Flutter or native. We show the calculation tier by tier in the article mobile app development cost.
How does Advertol choose a technology?
At Advertol, an app project starts not from the technology but from the business goal: the first step is a free strategy consultation, where what goes into the first version is determined. The proposal is prepared individually once the list of features, the roles and the integrations are clear; developer accounts are opened in the name of the client company.
An app's value lies in the system behind it, and Advertol's published projects show this side: the custom CRM built for Momento Travel collects enquiries from three channels in one panel, while in the AVA panel clients follow advertising results live. Advertol is an agency based in Baku: website and mobile app development, Meta and Google advertising, SMM, CRM and AI automation are all run by one team. The working process is described on the website and app development page.
Frequently asked questions
Is Flutter free?
Yes. Flutter is open source and free; you do not pay Google to use it. The costs lie elsewhere: the developers' work, the server, the Apple Developer Program ($99 a year) and a Google Play account (a one-off $25).
Is an app written in Flutter slower than a native app?
In ordinary business apps the user does not notice a difference: lists, forms, maps and payments work smoothly. The difference can show up in heavy graphics, complex video processing and games. Speed is affected more by the quality of the code than by the technology.
Flutter or React Native: which is better?
Both are mature technologies and are enough for most business apps. Flutter has the edge in custom design and animation, React Native in companies that have a web team. The deciding factor is the team's experience with that technology.
Can you build a website with Flutter too?
Yes, but not for every website. The Flutter web version suits app-like systems, such as an admin panel or a personal account. For a corporate website or online store that needs to be found on Google, ordinary web technologies give a better result.
Is Flutter hard to learn?
Not for someone with programming experience: the Dart language is simple and the official documentation is extensive. For those starting from zero, the fundamentals of programming have to be learned first. A business owner does not need to learn Flutter; it is enough to know what it is and what it changes.
If an app is written in Flutter, can you switch to another technology later?
Yes, but this means rewriting the part of the app that sits on the phone. The server, the database and the admin panel stay as they are. That is why the main asset is a properly built server side, and it is important that the source code belongs to you.
Conclusion
Flutter is a Google technology that lets you write an app for iOS and Android with a single codebase; its main alternatives are React Native and the native approach. For most business apps cross-platform is enough and saves budget; native is chosen for heavy graphics and deep device features. More important than the name of the technology are the team's live projects, the quality of the back end and your ownership of the code.
If you want to discuss the right technology for your app project and the scope of the first version, book a free strategy consultation or write to the Advertol team.