One Dart codebase, one rendering engine, two app stores. We build Flutter apps that stay smooth on mid-range phones, not just flagships, and tell you plainly when Flutter is not the right tool.
SIZ Group is a Flutter app development company based in Austin, Texas. Since 2018 we have designed and developed 678 apps for more than 465 clients across the USA, and Flutter is one of the frameworks we reach for when a product needs a custom, branded interface on both iPhone and Android without paying for two separate builds.
Flutter works differently from most cross-platform tools. It does not wrap the native buttons and lists that iOS and Android provide. Instead it draws every pixel itself through its own rendering engine, Impeller, which is the default on iOS and on modern Android devices. That is why a Flutter app looks identical on a Pixel and an iPhone 15, and why custom animations, charts and brand-heavy screens are cheaper to build here than almost anywhere else.
The same design also creates trade-offs. Flutter has to imitate platform conventions rather than inherit them, and some native features need a bridge into Swift or Kotlin. We explain those trade-offs on the first call so you choose Flutter for the right reasons, not because it was the default answer.
Every engagement is built around Dart, the Flutter widget tree and the native code your app actually needs.
We plan the widget architecture, choose a state management approach such as Riverpod or Bloc, and ship to the App Store and Google Play from a single repository. Build flavors keep development, staging and production builds cleanly separated from day one.
Because Flutter owns the canvas, we can build interfaces that would take weeks in native code: animated onboarding, custom charts, branded controls and shader effects. Impeller precompiles its shaders, which removes the first-run animation stutter older Flutter apps were known for.
When a feature needs an iOS or Android API that no package covers, we write the native side in Swift or Kotlin and connect it through platform channels or type-safe Pigeon interfaces. For C libraries we use Dart FFI directly.
If you maintain separate iOS and Android apps that have drifted apart, we can rebuild them in Flutter screen by screen. Flutter's add-to-app support lets new Flutter screens live inside an existing native app while the migration runs.
Flutter ships stable releases several times a year, and abandoned pub.dev packages are a common source of broken builds. We upgrade SDK versions, replace unmaintained dependencies and fix null safety or deprecation issues in older codebases.
The same Dart code can target web, macOS and Windows. We use this for admin dashboards and companion tools where sharing business logic matters more than a perfectly native desktop feel.
Our Flutter developers come from a hiring process that accepts only the top 4% of applicants, and the team brings more than ten years of collective experience. In practice that means people who understand the widget lifecycle, know why a rebuild is expensive, and can read the native stack trace when a plugin crashes on a specific Samsung model.
We also say no. Flutter is the wrong choice when your app depends mostly on native extensions such as iOS home screen widgets, Apple Watch apps, App Clips or heavy ARKit work, because those parts must be written natively anyway. It is also a weak fit when your team already ships a large React web app and wants to share code with it. In those cases we will point you to native development or React Native instead.
Talk to usOne team from first call to launch, with demos at every milestone.
We list every device feature your app needs and check each one against the Flutter package ecosystem. Anything without a reliable package is flagged early as native work so it is in the estimate.
Our designers decide where the app should follow Material 3 or Cupertino conventions and where it should use a fully custom look. We then turn the design system into shared theme data and reusable widgets.
We build feature by feature with a fixed state management pattern and a clear folder structure. You get regular test builds through TestFlight and Google Play internal testing.
Unit tests cover Dart logic, widget tests cover individual screens, and integration tests run real user flows on physical iOS and Android devices. Golden image tests catch visual regressions after upgrades.
We handle store submission, signing and release notes for both stores. After launch we keep the Flutter SDK and packages current and ship updates as the product grows.
These are the tools we use most often on Flutter projects, chosen per app rather than by habit.
Product grids, animated carts and branded checkouts suit Flutter's custom rendering. Our portfolio includes designs for a sports store, a gaming gear store and a workspace furniture store.
Grocery delivery with live tracking and driver booking flows need smooth maps and frequent state updates, which Flutter handles well with the right architecture.
Trail guides and travel discovery apps benefit from offline storage and rich visual layouts. We pair Flutter with local databases so key screens work without a signal.
Founders who need iOS and Android at once, with one team and one codebase, get the most value from Flutter's shared UI layer.
The biggest saving with Flutter is the user interface. Screens, animations and navigation are written once in Dart instead of twice in Swift and Kotlin, so design-heavy apps see the largest benefit. Apps that are mostly forms and lists save less, because those are quick to build natively too.
Cost rises with native work. Each feature that needs a custom platform channel, such as a specialized Bluetooth device, a payment terminal SDK or background location rules, adds Swift and Kotlin effort on top of Dart. Backend complexity, admin tools and the number of user roles matter as well.
Mobile apps at SIZ Group start at $4,500. Your final cost depends on scope and is confirmed in writing after a free consultation, where we map each feature to Flutter or native code so the number reflects what will actually be built.
Every project is scoped on a free call and confirmed in writing before work starts.
Flutter is used for full production apps on both stores. Release builds are compiled ahead of time to native ARM code and rendered through Impeller. The limits are about native extensions, not about stability or scale.
Avoid it when most of your value lives in native extensions like Apple Watch apps, home screen widgets, App Clips or advanced AR. Also avoid it if you want to share code with an existing React web app, where React Native is a better match. We will tell you this on the first call.
You do not need to write Dart yourself, but any developer who maintains the app will. Dart is easy to pick up for anyone who knows Java, Kotlin, Swift or TypeScript. We hand over documented code so a new team can continue the work.
It can, using Cupertino widgets and adaptive layouts, but those widgets are recreations of Apple's controls rather than the real ones. When Apple changes its design language, Flutter has to catch up. Many brands prefer one custom look on both platforms instead.
We have designed and developed 678 apps since 2018, and our developers come from the top 4% of applicants. As a Flutter app development company we also build native, so our advice on framework choice is not biased toward one tool.
Yes. We start with a code review covering the Flutter version, package health, state management and test coverage. You get a written list of risks and a plan before we change any code.
Book a free consultation and we will map your features to Flutter or native code before you commit.
