Justin Cappelle
Mobile app developer in Switzerland 🇨🇭
Mobile app development iOS and Android, from idea to app store.
Turnkey mobile appSwiftUI and React NativeApp Store and Google Play launch
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Your mobile app, from idea to launch
A successful app takes clear scoping, a design built for thumbs, solid code and a hitch-free launch. I handle all of it. You keep the final say on every decision.
01
Turnkey mobile app
You bring the idea, I take care of the rest. Scoping, mock-ups, development, testing and launch. You get an app that is ready to download.
Scoping and mock-ups
Development and testing
App store launch
Support after launch
02
Native iOS in SwiftUI
For an iPhone and iPad app that sits right at home in the Apple ecosystem. Native interface, smooth animations, widgets and notifications.
iPhone and iPad
Native Apple interface
Widgets and notifications
03
iOS and Android with React Native
One codebase for both platforms. Faster development, controlled costs and a smooth experience on iPhone and Android alike.
One codebase, two stores
Fast updates
TypeScript
04
Backend and launch
User accounts, database, payments, notifications. I build the backend for your app, then handle the launch and make sure it meets Apple and Google guidelines.
Accounts and database
Payments and notifications
App Store and Google Play
SwiftUI or React Native: which one is right for you?
Both technologies can produce an excellent mobile app. The right choice depends on your audience, your budget and your ambitions. I give you straight, honest advice during scoping.
Native Apple
SwiftUI
Ideal if most of your users are on iPhone, or your app needs to make full use of the Apple ecosystem.
- 100% native iOS and iPadOS interface
- Direct access to Apple's latest features
- Widgets, rich notifications, system integrations
iOS and Android in one go
React Native
Ideal if you want to reach everyone, fast, on a controlled budget.
- One codebase for both app stores
- Faster development and updates
- A smooth experience on iPhone and Android alike
What your app can do.
Every app is built around your needs. These are the features clients ask me for most often, and you can combine them to suit your project.
Bookings and appointments
Your customers book a slot in seconds, with automatic reminders.
In-app payments
Purchases, subscriptions or deposits, right inside the app.
Customer accounts
Sign-up, login, profile and history for every user.
Push notifications
News, an offer or a reminder, sent to the home screen at the right moment.
Geolocation
Maps, directions, store locations or real-time tracking.
Offline mode
The app keeps working without a connection and syncs later.
Loyalty
Points, perks and exclusive offers that bring your customers back.
Connected to your tools
Your CRM, till system, calendar or website, linked to your app.
Who is it for?
An app only makes sense if your customers or your team use it every day. These are the projects I work on.
Start-ups
Launch a first version to test your idea with real users, then grow it.
Shops and restaurants
Ordering, bookings and a loyalty programme in your customers' pockets.
E-commerce
An app that complements your online shop, with push notifications and checkout in two taps.
SMEs and field teams
An internal app for your staff: tracking, forms, scheduling, photos.
How I build your app.
A clear process in 4 steps. At every stage, you know where your app stands and what comes next.
- 1
Scoping
Together we pin down the goal of the app, the must-have features, the platform and the budget. You know exactly what will be delivered.
- 2
Mock-ups
I design every screen of your app. You click through the flow and sign off the design before a single line of code is written.
- 3
Build and testing
I build the app and the backend. You install a test version on your phone and try it out as the work progresses.
- 4
Launch and support
I publish the app on the App Store and Google Play, then keep it running with updates and new features.
Already have an app?
Is it slow, crashing, getting poor reviews, or simply not being used? I run a full audit of your iOS or Android app and hand you a clear report, with issues ranked by priority and concrete fixes.
Then it is your call: fix things with your current team, or hand the improvements over to me.
Request an app auditPerformance
Launch time, smoothness, battery drain.
User experience
User flows, sign-up, the screens where people drop off.
Bugs and crashes
Recurring errors and weak spots.
Security and data
Data storage, access, compliance with the Swiss FADP.
Code quality
Architecture, technical debt, how easy it is to take over.
Store listing
Visibility on the App Store and Google Play, reviews and ratings.
Mobile apps built to
last.
I design and build iOS and Android apps that run smoothly, are simple to use and easy to extend. Every screen is designed for one-thumb use, every feature answers a real need of your users, and the code stays clean so your next ideas fit in without a rebuild. You work directly with me, from the first mock-up to launch on the App Store and Google Play, and for every update after that.
SwiftUIReact NativeiOS and AndroidApp designTypeScriptBackend and APIsPaymentsPush notificationsIntegrations
+20
5.0
100% satisfied clientsTell me about your project,I'll handle the rest.
Describe what you need in a few clicks. I'll get back to you within 24 hours with a personal analysis and a free quote.
Association Artémont
Concerts and cultural events
“Justin brought together creativity, responsiveness and technical expertise to build a website that lives up to our standards. He listened, he was flexible, and the result is flawless. We will be calling on him again for our next projects without a second thought.”
Nathanaël B.
Alpura Lodges
“A modern, smooth website that is completely true to our image. Justin listened at every stage, came up with relevant ideas and delivered work of exceptional quality, on schedule. A serious, creative and passionate developer.”
Joel Lopez
ImmoSprint
“Impeccable work of flawless quality. Justin designed a website that matches our vision exactly, while bringing his own technical and creative expertise. The result: a professional, modern and extremely fast website.”
Romain B.
Leedy
“Available, committed and attentive, Justin built a website that goes beyond what I expected. He took the time to understand my needs and delivered a beautiful result, on time. I highly recommend him to anyone looking for a real professional.”
Association Artémont
Concerts and cultural events
“Justin brought together creativity, responsiveness and technical expertise to build a website that lives up to our standards. He listened, he was flexible, and the result is flawless. We will be calling on him again for our next projects without a second thought.”
Nathanaël B.
Alpura Lodges
“A modern, smooth website that is completely true to our image. Justin listened at every stage, came up with relevant ideas and delivered work of exceptional quality, on schedule. A serious, creative and passionate developer.”
Joel Lopez
ImmoSprint
“Impeccable work of flawless quality. Justin designed a website that matches our vision exactly, while bringing his own technical and creative expertise. The result: a professional, modern and extremely fast website.”
Romain B.
Leedy
“Available, committed and attentive, Justin built a website that goes beyond what I expected. He took the time to understand my needs and delivered a beautiful result, on time. I highly recommend him to anyone looking for a real professional.”
Yann Wegmüller
Chantemerle
“Meticulous, reliable work with excellent value for money. Justin delivers exactly what he promises, on time and with no unpleasant surprises. A dependable, rigorous developer. I recommend him without any hesitation.”
Yann Chaplet
Trio De Turismo
“Justin built our website to perfection. He respected our wishes while bringing his professional touch and sound advice. The result goes beyond our expectations. Excellent service, I recommend him without the slightest hesitation.”
Reviews translated from French
Questions I often get asked.
Can't find what you're looking for? Get in touch directly, I always reply within 24 hours.
Get in touchEvery project is different. A first version with the key features, built to test your market, can often be developed in 4 to 8 weeks. For an app with more complex features, allow 3 to 6 months instead. It all starts with precise scoping.
SwiftUI is Apple's interface framework. It is the best choice if your audience is mostly on iPhone or if the app needs to make full use of the Apple ecosystem. React Native lets me build a single app for both iOS and Android, which cuts both timelines and budget. I recommend the best fit for your project during scoping.
You have one point of contact who designs and builds your app himself. Nothing gets lost between a salesperson, a project manager and a developer. You pay for the work done, not for an agency's overheads.
Yes. I start with an audit of the app: performance, user experience, bugs, security, code quality and store listing. You get a report with clear priorities, then I can take on the fixes, a redesign or new features.
Yes. User accounts, database, APIs, payments, notifications. I build your app's backend, either custom or with a platform like Supabase or Firebase, depending on the project.
I take care of everything: developer accounts, store listings and screenshots, submitting builds and following the review process. I make sure the app meets Apple and Google guidelines to avoid rejections.
You do. Once the project is paid, you hold all rights to the source code. I can also set everything up on your own accounts (app stores, hosting, code repository) so you are in control from day one.
Technologies and specialities
The areas I know best for building custom websites, interfaces and apps.