Your app from scratch
From scope to the App Store, in Swift and SwiftUI. You test every version on your own iPhone through TestFlight before launch.
See iOS and Mac app development →Swift · SwiftUI · App Store
iPhone and Mac apps, from scope to the App Store.
Carvalho Karsten is an app development company that builds native apps in Swift and handles App Store publishing. The team works remotely from Santa Catarina, Brazil, for clients in the US, Europe and Brazil.
DevbeltmacOS · Swift
Approved for the App Store
- Apple Developer account and App Store Connect agreements
- TestFlight builds for your clients and your team
- Store listing: text, screenshots and privacy policy
Bookings
Haircut and beard
Today, 2:30 PMConfirmed
Today, 2:30 PMConfirmed
Manicure
Tomorrow, 9 AM
Tomorrow, 9 AM
Brows
Friday, 4 PM
Friday, 4 PM
What Carvalho Karsten does
Carvalho Karsten turns your app idea into Swift code, sends every build to your iPhone 
through TestFlight and stays with you until Apple approves it.
Bookings
Haircut and beard
Today, 2:30 PMConfirmed
Today, 2:30 PMConfirmed
Manicure
Tomorrow, 9 AM
Tomorrow, 9 AM
Brows
Friday, 4 PM
Friday, 4 PM
TestFlight
You test on your iPhone before launch
Every build arrives through TestFlight. You install it, use it day to day and send changes before the app goes to Apple.
Illustration: booking app for iPhone
App StoreDevbelt, the studio’s own Mac app, passed Apple’s App Store review.
Swift and SwiftUIMac apps built in-house, in the same language as iPhone apps.
US and BrazilPartners with 20+ years in technology and a base on Cape Cod, Massachusetts.
Development · Consulting · After launch
Three ways to work with Carvalho Karsten
App Store publishing
The team sets up your developer account, store listing and submission, and updates the app when Apple asks for changes.
See App Store publishing →Maintenance
Updates for each new iOS and macOS release, bug fixes and new features, with a monthly scope you agree on.
See app maintenance →App Store publishing
Did Apple reject your app?
Carvalho Karsten reviews the app, fixes what Apple flagged and resubmits it. This also covers apps built with AI tools such as Lovable, Cursor, Rork and Bolt.
Apple Developer account and App Store Connect agreements
TestFlight builds for your clients and your team
Store listing: text, screenshots and privacy policy
Replies to App Review until approval
Selected in-house apps
A selection of the apps the team built in Swift and SwiftUI.
Devbelt Approved for the App Store Offline tools for developers, plus a scanner that finds keys and passwords left in your code. 
Limpador Shows what fills your disk and moves to the Trash only what you select. WhereIsMyRAM CPU, memory, disk and network in the menu bar, with a Liquid Glass panel. 
NoteAssistant Transcribes meetings in real time and suggests replies during the call. 
Adega Runs Windows programs on the Mac, with a game library. What an app costs
These ranges are market references for the first version of an app, the minimum viable product (MVP). Your price comes from the project review: development stages, integrations and required changes.
- United States
- $50,000 to $100,000
- Europe
- from €10,000
- Brazil
- R$50,000 to R$250,000
How the work runs
- Project reviewYou describe the idea, and the team maps stages, integrations and risks.
- ProposalScope, timeline and price for each stage, in writing.
- DevelopmentTestFlight builds you test on your own device.
- PublishingSubmission to the App Store and follow-up with App Review.
- MaintenanceUpdates for each new iOS and macOS release.
Who builds the apps
Thiago Do Carmo
Partner · CEO
Has lived on Cape Cod, Massachusetts, for 21 years and runs six companies, including DockPlus AI.
Gustavo Henrique Karsten
Partner · CTO
Engineer with more than 20 years in technology. Leads the architecture and code of every app.
Frequently asked questions
Does Carvalho Karsten build Android apps?
No. The team works on iPhone, iPad and Mac, in Swift. If your project also needs Android, the project review lays out the options and the cost of each.
How long does it take to build an app?
In the market, a first version usually takes 3 to 4 months. The timeline for your app comes from the project review, stage by stage.
Can you publish an app I already built?
Yes. The App Store publishing service reviews your app, prepares the store listing and follows App Review until approval.
How does a remote engagement work?
The team works from Santa Catarina, Brazil, 1 to 2 hours ahead of Boston, with video calls and TestFlight builds. The US business address is in Hyannis, Massachusetts.
Which languages do you work in?
English, Portuguese and Spanish.