App development for iOS and Android
Apps that work in everyday life
A good app hardly gets noticed in everyday use: it starts quickly, works even in a basement with no signal and gets its job done in just a few taps. There is more to it than the interface on the smartphone – a back end that stores and distributes data, interfaces to your existing systems, and operations that keep an eye on updates, security and new operating system versions.
That is why we develop apps as a complete system: app, back end and integration from a single partner. This gives you one point of responsibility when data does not arrive, a new iOS version comes out or a connected system changes. Beforehand, we check honestly with you whether it really has to be an app – sometimes a web application covers the need more cost-effectively.
Who we develop apps for
Apps for field staff. Record service reports, working hours, photos and the customer's signature right on site – even without a connection, with automatic sync as soon as there is signal again.
Internal applications. Checklists, inspection reports or warehouse processes that currently run on paper or in spreadsheets and are done faster on a mobile device.
Customer apps. Apps your customers use to access information and services – in your brand's design and, if required, in several languages.
Apps as a product in their own right. Subscription models that apply across all platforms and are billed via the App Store, Google Play or Stripe – just as we have done for our own product Inventary.
Native development for iPhone and Android
We develop native apps: with Swift and SwiftUI for iPhone and iPad, and with Kotlin and Jetpack Compose for Android. Native apps use the camera, location and local storage directly, follow the interaction patterns of their platform and are easy to develop further when new operating system versions arrive.
Our apps for ClicClic show how far this goes: they control professional cameras from Canon, Nikon and Sony directly and transfer the photos while the event is still going on. We usually develop the back end with Ruby on Rails. It provides an API for the app, powers a web interface for the office and connects ERP, CRM or accounting systems via interfaces.
From our projects: the Stenger service app
Since autumn 2025, the service technicians of the Stuttgart pump specialist Stenger have documented their jobs in an app for iPhone and Android: findings, spare parts from the item master, photos and the customer's signature. The report reaches the office right after the job, even if there was no signal in the plant room – the app syncs in the background as soon as it has a connection. By the next morning, all data is in the GDI ERP system without anyone having to type up paper notes. Read the full story in the Stenger case study.
How much does it cost to develop an app?
Based on our cost model, a simple app for iOS and Android costs about €21,000–38,000, an app with sign-in, back end and an interface €50,000–89,000 and an extensive native app €150,000–270,000 – all net, including project management and quality assurance.
Which factors drive the price and which ongoing costs come on top is explained in our guide How much does an app cost?. For an estimate for your idea, the project cost calculator takes just a few minutes.
How your app comes to life
- Free initial consultation: clarifying target group, features and platforms
- Concept and a clickable prototype to try out on your smartphone
- Development of app and back end in short iterations with test builds
- Publication in the App Store and Google Play, operation and updates
- Free initial consultation: clarifying target group, features and platforms
- Concept and a clickable prototype to try out on your smartphone
- Development of app and back end in short iterations with test builds
- Publication in the App Store and Google Play, operation and updates
Frequently asked questions about app development
Native app, web app or both?
A native app pays off when the camera, offline use, device features or a presence in the app stores are at the heart of it. A web app, on the other hand, runs on any device without installation; our product Stundenplan-Digital, for example, is a progressive web app that can be used on a smartphone without an app store. Often the best solution is both: a web interface for the office and an app for use on the go, both accessing the same back end.
Does the app work without an internet connection?
Yes, if it is built for it. The app then stores data locally and syncs it in the background as soon as a connection is available again. This capability has to be planned from the outset, because it affects the data model and synchronisation. The Stenger service app works this way: technicians simply keep documenting, even in a plant room with no signal.
How does the app get into the App Store and Google Play?
To publish it, your company needs a developer account with Apple and Google; your name then appears as the provider in the store. Both stores review apps before publication. We prepare the submission and support you through the review process. Internal apps for employees can also be distributed without a public store listing.
What happens after the launch?
Apple and Google release new versions of their operating systems every year, libraries receive security updates, and users ask for new features. An app therefore needs regular care. If you wish, we take over maintenance and support, operate the back end and develop the app further.
Can you take over our existing app?
Yes. We first get an overview of the code, back end, store accounts and dependencies and show you where action is needed. We then bring the app up to current versions and develop it further. How we modernise software that has grown over time is described on our page about legacy modernisation.
Didn't find your question?Get in touch
Tell us who will use it and what problem it solves – and we will show you how we would build it.