---
title: "Cross-platform apps — SwiftUp"
description: "A single codebase, built to the same standard as native: iOS and Android shipped together, without doubling teams or timelines. The bespoke work stays whole — your product, your journeys, your interface."
canonical: "https://swift-up.com/en/savoir-faire/apps-cross-platform"
lang: "en"
---

# Cross-platform apps

One codebase, two platforms.

One build, and your app ships on iPhone and Android together.

[Start a project](https://swift-up.com/en/contact) [See our method](https://swift-up.com/en/methode)

Built for

-   Startups launching
-   MVP & v1
-   iOS + Android launches

Your app

Illustrative SwiftUp mockup — generic demo interface.

Your app

Illustrative SwiftUp mockup — generic demo interface.

**Your turn.** Change a tab or a setting: both phones follow. Change a tab or a setting: both phones follow.

-   What we bring
-   Behind the scenes
-   Deliverables
-   The right fit

What we bring

## Two platforms, one momentum.

We write your application once and ship it on iOS and on Android. One team, one schedule, the same standard as native.

### One codebase. Two apps.

Screens, journeys, rules: written once, running on iOS and on Android. What is decided for one holds for the other — nothing is duplicated, nothing drifts apart.

### iOS and Android, the same day.

Every release lands on both stores at once. Your users move forward together.

### Native, when it's needed.

Camera, Bluetooth, payments: where the device demands it, we write a native module. Occasional, targeted.

### Releases that ship without friction.

Tests, build, store submission: the chain is automated. A fix never stays stuck on someone's machine.

### True to each platform.

A shared base doesn't mean a generic app: every screen respects the habits of iOS and of Android.

Behind the scenes

## What sits behind the screen.

Two apps, a single build. Here is how one codebase becomes a product on each platform.

1.  What the user touches

    ### 

    A single design, rendered with each platform's native components.

    -   React Native

2.  What is written once

    ### 

    Screens, journeys, business rules: one TypeScript codebase, for iOS and for Android.

    -   TypeScript
    -   Expo

3.  What talks to the device

    ### 

    When a feature needs the hardware, we drop down to native — only where it is useful.

    -   Swift
    -   Kotlin

4.  What builds and publishes

    ### 

    An automated chain that tests, builds and sends both apps to the stores.

    -   EAS
    -   App Store · Play

Deliverables

## What you get

-   ### Shared iOS / Android architecture

    A single codebase, structured so that both apps always move forward together.

-   ### An interface true to both platforms

    A shared design, adjusted where iOS and Android each have their own habits.

-   ### Sync and offline mode

    The app stays usable without a network, and catches up as soon as the connection returns.

-   ### Build and release pipeline

    Building and submitting to the stores are automated: a new version ships in a few steps.

-   ### Ongoing fixes and improvements

    An improvement is developed once and reaches both platforms.

Stack & technologies

-   React Native
-   Expo
-   TypeScript
-   Native modules
-   EAS

Indicative — the final stack is chosen to fit your project.

The right fit

## Is this the right approach for you?

We don't sell the same answer to everyone. Here is when this approach is the right one — and when another will serve you better.

### It's the right approach if…

-   You are launching iOS and Android at the same time.
-   You want to put a first version in your users' hands, then evolve it quickly.
-   Your product is built on accounts, content, forms and exchanges.
-   You care that both platforms move at the same pace.

### Look instead at…

-   [Native mobile apps if your product leans on the hardware — augmented reality, heavy Bluetooth, video — or aims for a finish specific to each platform.](https://swift-up.com/en/savoir-faire/apps-mobiles-natives)
-   [Custom web applications if your users mostly work on a computer.](https://swift-up.com/en/savoir-faire/applications-web)

Unsure between two approaches? We settle it together, at the framing stage.

## We also build.

Same studio, same standards. Only the form changes.

-   [Custom web applications The product that runs your business. Explore](https://swift-up.com/en/savoir-faire/applications-web)
-   [Websites An online presence that earns trust. Explore](https://swift-up.com/en/savoir-faire/sites-web)
-   [Native mobile apps The best of iOS and Android. Explore](https://swift-up.com/en/savoir-faire/apps-mobiles-natives)

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