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Cross-Platform App Development

Cross-platformmobile app development services for iOS and Android, with honest advice on the stack.

One team, one codebase, two app stores. We build with React Native or Flutter when it fits your product, and tell you plainly when native Swift and Kotlin would serve you better.
Get stack advice

The framework matters less than choosing it for the right reasons.

React Native, Flutter and native development all produce good apps. They differ in cost, hiring, performance limits and how well they fit the team you already have. We've built with all three, so our recommendation is based on your product, not on the only tool we know.

What goes wrong with cross-platform apps

01

The wrong framework for the job

Teams pick a framework because it's popular, then hit its limits when the product needs heavy graphics or deep device access.
02

Apps that feel foreign on both platforms

A shared UI that ignores iOS and Android conventions confuses users on each side.
03

Native modules nobody can maintain

Camera, Bluetooth or payments need native code, and the team only knows JavaScript or Dart.
04

Framework upgrades pile up

Skipped React Native or Flutter versions turn a routine update into a multi-week project.
05

Performance surprises

Long lists, animations and startup time get slow once real data and real users arrive.
06

Old hybrid apps that hit a wall

Web view wrappers built years ago can't keep up with what users now expect from an app.

React Native vs Flutter vs native: our honest take

There's no single answer. Here is how we usually advise clients.

React Native

  • Your team already works in React and TypeScript
  • You want to share logic with a web app
  • Large library choice and a big hiring pool

Flutter

  • You want pixel-identical UI on both platforms
  • Custom design and rich animation matter
  • A new team without strong web background

Native Swift and Kotlin

  • Heavy use of camera, sensors or background work
  • Top performance is the product
  • Platform features must ship on day one

Mixed approach

  • Shared app with native modules where needed
  • Native screens inside a cross-platform app
  • Gradual move from an old hybrid app

Signs cross-platform is right for you

A shared codebase pays off most when several of these are true.

1

You need both stores at once

Your customers are split between iPhone and Android and you can't launch on one and wait.

2

Budget covers one team, not two

Separate iOS and Android teams would double the cost of every feature.

3

Your product is mostly screens and data

Forms, feeds, catalogs, bookings and dashboards are where shared code works well.

4

You already have web developers

Your team knows React and TypeScript, which makes React Native a natural next step.

5

You want to test the market fast

An MVP on both platforms tells you more than a native app on one.

6

Your hybrid app is showing its age

An older web view app feels slow and you need a modern replacement.

What we do

Our cross-platform and hybrid mobile app development services

Stack selection

A short, written comparison of React Native, Flutter and native for your specific product.

React Native apps

iOS and Android apps in React Native and TypeScript, sharing code and skills with your web team.

Flutter apps

Flutter mobile app development services for products that need a custom, consistent UI on both platforms.

Native modules

Swift and Kotlin code for the parts a shared framework can't handle well.

Hybrid app replacement

Moving old web view or Cordova-style apps to React Native or Flutter in stages.

Framework upgrades

Bringing outdated React Native or Flutter versions and libraries up to date.

Testing on both platforms

Automated and manual QA on iPhones and Android devices before every release.

Dual store release

App Store and Google Play submissions, reviews and rollouts handled together.

Technologies we use for cross-platform apps

React Native and Flutter for shared code, Swift and Kotlin for native modules, and a backend that serves both apps.

React
TypeScript
JavaScript
Swift
Kotlin
Node.js
PostgreSQL
AWS
GitHub Actions
Who is this for

Teams that need iOS and Android without two teams

Startups building an MVP

You need to reach users on both platforms quickly and learn before spending more.

Product companies with a web app

Your React team and APIs can power a mobile app with less duplicated work.

SMBs with a limited budget

One codebase keeps the cost of building and maintaining your app under control.

Founders unsure about the stack

You've heard conflicting advice and want a clear recommendation with reasons.

Where can we help?

Choose a stack

A clear comparison and recommendation for your app.

Build a new app

Design, development and release on both stores.

Replace a hybrid app

Move from an old web view app to a modern one.

Merge two native apps

Plan a move to one shared codebase where it makes sense.

Upgrade the framework

Catch up on skipped versions and libraries.

Add native features

Camera, Bluetooth, payments and other native modules.

How we deliver a cross-platform app

01

Stack decision

We review your product, team and budget and recommend React Native, Flutter or native, in writing.

02

Discovery and design

Core flows and screens designed once, with platform differences planned where users expect them.

03

Shared development

Engineers build features once for both platforms, adding native modules only where they are needed.

04

Testing on both platforms

QA on iPhones and Android devices, so a fix on one side doesn't break the other.

05

Release to both stores

App Store and Google Play submissions prepared and handled in parallel.

06

Support and upgrades

Framework updates, OS changes and new features after launch.

How we work

Two ways to start

Discovery Sprint

most popular

2 weeks, fixed price

Then a fixed-scope build or a dedicated team.

For new apps where the stack, scope and budget aren't settled yet.

React Native vs Flutter vs native comparison

Core flows and clickable prototype

Architecture and backend plan

Scope, timeline and cost estimate

A plan you own, whoever builds it

Book discovery

Dedicated mobile team

Engineers, QA and a lead

Monthly, team-based.

For products that already know what to build and need a team to build it.

Cross-platform and native skills in one team

Regular demos and test builds

QA on both platforms included

Store releases handled

Scale the team with your roadmap

Meet the team

Mobile products we've shipped

E-COMMERCE & MARKETPLACE

Flashfood Grocery marketplace

USA
Canada
$247M
SHOPPER SAVINGS
Before
→
after
↓
Rapid scale across 700+ stores
↑
$247M in shopper savings
↓
Mobile reliability under pressure
↑
$16.5M raised
↓
Engineering capacity stretched thin
↑
1,600 stores served
↓
No clear path to recovery
↑
Sustained delivery cadence
Food delivery

Optimizing and controlling delivery for a Pizzeria Chain

3.5 mo
to MVP launch
Read the case study →
Mental health

Mobile app for mental health improvement

Read the case study →

Make the most of the experienced team

We are a global team of
creative
and
strategic thinkers
who specialize in building custom digital products
from scratch. Our main goal is to
deliver high-quality solutions
that meet our clients' needs.
We are a global team of
creative
and
strategic thinkers
who specialize
in building custom digital products
from scratch. Our main goal is to
deliver high-quality solutions
that
meet our clients' needs.
Learn more
85%
recurring customers
12M
the biggest fundraising round by one startup
X3 MRR
growth of partner's business in 5 mos
2 weeks
for project start
5+ years
av. partnership duration with SMBs and product companies

Why Gilzor

We build with React Native, Flutter, Swift and Kotlin, so we can recommend what fits your product instead of what fits our bench.

What we bring

Mobile experience

7+ years building iOS and Android products.

Launch track record

70+ products launched for our clients.

Fast start

Projects can start in about two weeks.

Long partnerships

Average partnership with SMBs and product companies is 5+ years.

Full product team

Design, mobile, backend and QA from one partner.

What makes us different

No framework bias

We'll recommend native if cross-platform isn't right for you.

Native skills in-house

Swift and Kotlin engineers write the native modules.

Platform-aware design

Shared code, but each platform still feels familiar.

Upgrade discipline

Framework versions kept current, not left to rot.

Overlap with US hours

Our engineers in Europe overlap with part of the US working day.

What our clients
frequently ask

Should we choose React Native or Flutter?

React Native is usually the better pick if your team knows React and TypeScript or you want to share code with a web app. Flutter suits products with a highly custom UI and teams starting fresh. Both are solid; the right choice depends on your team and product.

When is native development a better choice?

When the app relies heavily on device hardware, background processing, complex graphics or new platform features on release day. In those cases separate Swift and Kotlin apps are often worth the extra cost.

How much code is shared between iOS and Android?

Most of the business logic and screens are shared. The amount of platform-specific code depends on how much native functionality your app needs. We estimate it during discovery.

What is the difference between hybrid and cross-platform apps?

Older hybrid apps run a website inside a web view. React Native and Flutter render real native or custom UI and feel much closer to a native app. We help teams replace older hybrid apps when they hit their limits.

Can you move our two native apps to one codebase?

Sometimes. We first check whether it would actually save effort, then plan a gradual move so you don't stop shipping features. Sometimes keeping native is the better answer, and we'll say so.

How is a cross-platform project priced?

It usually starts with a 2-week fixed-price Discovery Sprint. After that you choose a fixed price for the agreed scope or a monthly dedicated team.

No sales pitch

Not sure which stack to choose?

Tell us about your app, your users and your team. We'll reply with a recommendation for React Native, Flutter or native, and why.

Next, a few optional questions so the first call is useful. We use your details only to reply to your request. Privacy Policy

contacts@gilzor.com
Poland, Warsaw, Office 58, street Adama Mickiewicza 37, 01-625
Cyprus, Limassol, Office 113E 3030, BLOCK A, AGIOS PAVLOS, 228, Makariou III
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