Flutter migration
Rewriting a Native App in Flutter: When It Pays Off and How the Move Runs
Two native apps mean two codebases, two teams and every change made twice. Rewriting a native app in Flutter can end that, or it can cost months and change nothing your users notice. Here is how to tell which, and how a rewrite runs when it is the right call.
Short answer
Rewriting a native app in Flutter pays off when you maintain separate iOS and Android apps that do the same job, every change is built twice, and the product is mostly screens, forms and data rather than deep platform features. It rarely pays off when the app depends on platform specific features, a strong native team already ships quickly, or the code is healthy. The move runs as an audit, a parity scope, a rewrite that keeps the same store listings and user data, and a staged release, or screen by screen inside the existing app.
Why companies rewrite native apps in Flutter
The usual trigger is not the technology. It is the cost of doing everything twice: two codebases, two sets of bugs, features that land on iOS weeks before Android, and a release plan built around the slower team. Flutter puts both platforms on one codebase, so a change is designed, built and tested once.
That benefit is real, but a rewrite is also a project with no new features at the end of it. Before deciding, it helps to weigh the signals honestly. As a Flutter app development company, we are not neutral, so the list below includes the cases where we would advise against it.
When rewriting a native app in Flutter pays off, and when it does not
Both apps do the same job. The iOS and Android versions show the same screens and run the same business rules, so most of the work is duplicated.
One platform always lags. Features ship on one platform first and the other catches up later, or never, and support handles the difference.
The code is already due for a rebuild. If one or both apps need a major rework anyway, rebuilding once in Flutter costs less than rebuilding twice.
The product is the platform. Apps built around platform specific features end up writing native code on both sides anyway. Our article on when not to use Flutter lists these cases.
Strong native teams already ship fast. If both teams deliver on time and the code is healthy, a rewrite trades a working setup for months of risk.
The real problem is elsewhere. Slow releases caused by an unclear backlog, a fragile backend or missing tests will follow the app into Flutter unchanged.
If the signals are mixed, start with an audit of both codebases before committing. When a company brings us an existing app, that audit is the first step, and it ends with an honest view of whether continuing beats rebuilding. The same approach is described in our guide to taking over an existing mobile app.
Three ways to move a native app to Flutter
A rewrite does not have to be one big switch. There are three realistic paths, and the right one depends on how large the app is and how much risk the business can carry in one release.
Full rewrite, one release
The whole app is rebuilt in Flutter and replaces both native apps in a single update.
Best whenThe app is small to medium and both versions need rework anyway
Watch out forA long period with no new features for users
Screen by screen
New and rewritten screens are built in Flutter and embedded in the existing native apps until nothing native is left.
Best whenThe app is large and the business cannot pause feature work
Watch out forTwo technologies in one app for a while, and plugins that assume a full Flutter app
Keep native, share the rest
The apps stay native, and duplication is cut in the backend and shared business logic instead.
Best whenThe apps rely heavily on platform features
Watch out forInterface work is still done twice
The screen by screen path uses what Flutter calls add to app: a Flutter module inside an existing iOS or Android app, with some screens rendered by Flutter and others by native code. It lowers the risk of any single release, at the price of running two technologies side by side until the move is finished.
How a native to Flutter rewrite runs
The steps are the same whichever path you choose. What changes is whether they happen once for the whole app or once per group of screens.
Audit both apps
Screens, business rules, native features, third party SDKs and stored data, compared across iOS and Android.
Write the parity scope
Every screen that must exist in Flutter, plus features to drop because users no longer need them.
Map native features
Anything Flutter does not cover gets a plugin or a small piece of native code called through platform channels.
Rebuild on the same backend
The Flutter app talks to the existing APIs, so the server side does not move at the same time as the app.
Test against the old apps
Each flow is checked side by side with the native version, on real devices, before release.
Release in stages
The update goes to a small share of users first through staged rollout, then to everyone once crash rates and reviews look right.
The parity scope is where a rewrite saves or loses money. Rebuilding screens nobody uses is the most common waste, and a rewrite is the cheapest moment to drop them. Our guide to adding features to an existing Flutter app covers what comes after the move.
A good rewrite is one your users never notice, except that both platforms start getting the same features on the same day.
What users must not notice after the rewrite
The Flutter version arrives as an update to the same app, not as a new app. These are the things that decide whether it feels that way.
- The same store listingThe Flutter build keeps the existing bundle identifier on iOS, the application ID and signing on Android, so it installs over the old app and keeps its ratings and reviews.
- Data stored on the phoneAnything the native app saved locally, such as drafts, settings or offline records, is read and moved on the first launch of the new version.
- Signed in sessionsTokens are carried over where possible, so users are not logged out by an update they did not ask for.
- Links and notificationsDeep links keep the same addresses, and push notifications keep arriving through the same setup.
A rewrite that paid off: Reflectly
Reflectly, a journaling app, launched on iOS first. After six months of trying to fix its existing Android version, the team of two engineers rewrote the app in Flutter and shipped Reflectly 2.0 on Android and iOS together, including a premium subscription.
The team also moved from releases every two weeks to weekly releases, with features landing on both platforms at once. The figures are reported by the company in a case study published by Google.
Source: Android Developers case study
Reflectly fits the first column of the signals list: two platforms doing the same job, one lagging badly, and code that needed rebuilding anyway. More products built this way are in our list of Flutter app examples.
What a rewrite costs and how it is priced
A rewrite is priced like a new build of the parity scope, with one advantage: the product decisions already exist in the old apps, so discovery is shorter. The main cost drivers are the number of screens kept, the native features that need plugins or platform code, and how much data has to move on the first launch.
We price rewrites the same way as new projects: one fixed number for a written scope, agreed before work starts. See how fixed price app development works and the current bands on our pricing page. If you are still choosing between technologies, our comparison of Flutter vs React Native for business apps covers the other cross platform option.
About the source
Who is answering this?
- Company
- Apps Value, mobile app development agency
- Location
- Kraków, Poland
- Markets served
- United States, Western Europe, Nordics
- Experience
- 6 years, 19+ projects delivered, 13+ positive client reviews
- Technologies
- Flutter, React Native, NestJS, Supabase, PostgreSQL, AWS, Google Cloud
- Engagement models
- Fixed price contracts and dedicated development teams
- Existing apps
- Every takeover or rewrite starts with an audit of the current code
FAQ
Should I rewrite my native app in Flutter?
Rewrite when your iOS and Android apps do the same job, every change is built twice and the product is mostly screens, forms and data. Keep native when the app depends on platform specific features, strong native teams already ship quickly, or the code is healthy.
Can I migrate a native app to Flutter gradually?
Yes. Flutter can run inside an existing iOS or Android app as a module, so screens can move one group at a time. It lowers the risk of each release, but the app runs two technologies until the move is finished.
Will users have to download a new app?
No. The Flutter version keeps the same bundle identifier on iOS and the same application ID and signing on Android, so it arrives as an update to the existing app with its ratings and reviews.
Will users lose their data or be logged out?
Not if the rewrite plans for it. Data the native app stored on the phone is read and moved on the first launch, and sessions are carried over where possible, so the update feels like any other.
Do we need to change our backend to move to Flutter?
Usually not. The Flutter app can use the existing APIs, which keeps the rewrite to the app alone and avoids moving the server side at the same time.
How is a native to Flutter rewrite priced?
Like a new build of the screens you keep, with a shorter discovery because the product decisions already exist. We agree one fixed price for a written parity scope before work starts; current bands are on our pricing page.
Related guides
Written by
Thomas Siudut
Co-Founder and CEO, Apps Value
Thomas sets the company's long term strategy and direction, identifies market opportunities, and owns business development and client acquisition. He builds strategic partnerships that last beyond a single project. He works with clients from the first strategy conversation, so their business goals, not just their feature list, drive every decision.
Maintaining two native apps that do the same job?
Tell us about both apps. We will tell you honestly whether a Flutter rewrite pays off for you, which path fits, and what the parity scope would look like.