App Development Agency You know what your app costs. Before it gets built.

In 21 days you click through your app, before a single line of code is written. Then you get one fixed price for everything. Many clients come to us because their last agency cost more than planned.

Louis Nell, Managing Director of KNGURU
  • App screen for Red Bull Salzburg
  • Scoops: recipes from food creators in the app
  • App with jobs and teams for tradespeople
  • App for booking e-shuttle rides
  • App for booking offices and rooms
  • Community app for dog owners with map and chat
  • App with bedtime stories
  • Augenzeuge: tips and messages in the app
  • Daycare app with attendance, schedule and chat
  • RadlScout: find and sell bikes
  • Funellab: website for recruiting through social media
  • Elaris: website for an electric car

Recognized for design, user experience and digital innovation

Nine out of twelve reviews say the same thing: we push back when something won't work for users.

  • OMR Reviews Proud Partner 2026: UX Agencies
  • OMR Reviews Proud Partner 2026: App Development Agencies
  • German Stevie Awards 2026: Gold for PetPlanner

New app or existing software, we do both

Most companies come to us with an app that is already live. The others with an idea. Pick your path; both start with a free call.

Idea or concept

New app

You want an app built and want to know up front whether it will catch on. First the prototype in 21 days, then the app at a fixed price, then we help you get users.

  1. Prototype in 21 days, €5,490, fully credited
  2. App at a fixed price from €10,000
  3. 90 days to get your first users

Already live, needs to get better

Existing app or software

Your app is showing its age, your developer has left or your agency isn't delivering. We take over the code, modernize the interface and tech, and win your users back. No prototype needed, we start within days.

  1. Code takeover instead of a rebuild
  2. UX/UI redesign while the app stays live
  3. Design and dev team from €2,699 a month

Special casesDevelop your AI prototype furtherYour own software instead of subscriptionsJust get more users

January 2026Today

60,000

users in DeepDays, our own app

How our own app went from 0 to 60,000 users.

DeepDays is our app for car events. Every euro spent on ads was our own. What worked there, we apply to your app.

Today

60,000
registered users
€1M+
in ticket sales through the app
350+
events
4.8 ★
in both stores

How we did it

  1. 01PositioningEvery car meet in one app. One clear reason to download it.
  2. 02UX/UIEvent pages that sell. Tickets go straight into the wallet.
  3. 03Measured marketingAds per event in the local area, tracked all the way to the ticket sale.

How much does your app cost?

The more features your app needs, the higher the development costs usually are. That's why we start lean and expand later.

Fixed-price app development in 4 steps

With more than 200 projects and our own startup behind us, we know what it takes to build an app. Four steps, each with a fixed price. After each one, you decide whether to continue.

  1. Prototype in 21 days

    €5,490

    You click through your app before any code is written. Then the fixed price is set.

    fully credited toward the build

    More on the prototype
  2. Keep building

    from €10,000

    If you like the prototype, we build in fixed stages. You test the app yourself after each one.

  3. Your finished app

    included

    Login, payments, data privacy and both stores are included. The code and accounts are yours.

  4. Get users

    90 days

    We help you get your first users. That's how DeepDays reached 60,000.

    Price after the free analysis

    More on growth

Different types of apps

The right type of app depends on who uses it and where. We build all three, and in the expert call we tell you which one is worth it for you.

  1. Before any type of app

    Clickable prototype

    You click through your app before any code is written. Then you know which app type you need and what it costs.

    Runs on
    your phone
    Duration
    21 days
    Credited
    in full
    Price
    €5,490
  2. Browser-based application

    Web App

    Web apps cost less to build and are a good fit for B2B applications and dashboards.

    Runs on
    any browser
    Good for
    B2B apps, dashboards
    Tech
    React
    Price
    from €10,000
  3. iOS and Android application

    Cross-Platform

    Cross-platform apps are hard to tell apart from a native app. The advantage: iOS and Android share one codebase.

    Runs on
    iOS and Android
    Code
    one codebase for both
    Tech
    React Native, Flutter
    Push
    yes
    Price
    from €20,000
  4. Separate for iOS and Android

    Native App

    We build native apps separately for iOS and Android. That pays off when your app needs deep access to the camera, sensors or system features.

    Runs on
    iOS and Android, separately
    Good for
    camera, sensors, devices
    Tech
    Swift, Kotlin
    Price
    from €30,000

Have an app built without it costing more than planned.

If you want to have an app built, you will probably compare several offers. Check each one for these four things, ours included.

A price before the build
After 21 days you click through your prototype. Then you get a fixed price for the whole app. The prototype costs €5,490 and is fully credited toward the build.
A schedule you can see
Depending on scope, development takes three to six months. Every two weeks you get a demo on your phone.
Everything in your name
Code, design and store accounts belong to you. You can continue with another team at any time.
Help after launch
An app in the store has no users yet. If you want, we win the first ones with you in the 90 days after launch.

Built for clients. In use today.

A Gold Stevie Award, 200,000 festival visitors, 4.4 stars on Google Play. Eight of over 200 projects, all live, every screen real. Two more we can name but not show.

See all projects

Cutting corners on development puts your profits at risk

Building with AI is fast today. It gets expensive when no one decides up front what's worth building, when payments and app stores are added as extras, and when no one brings in users after launch.

  1. 01

    Decide before you build

    In 21 days you click through your app's main flows and know whether it's worth building. That's how the Glücksgefühle Festival, with 200,000 visitors, got its prototype.

  2. 02

    Fixed price all the way to the stores

    Login, payments, stores and data privacy are part of the fixed price, not extras added later. Scoops sells subscriptions in its food app, Smartmove manages thousands of vehicles through the interface we built.

  3. 03

    90 days to get users to stay

    After launch, we work on positioning, UX/UI and measured marketing to get users active and paying. These three levers took DeepDays from zero to 60,000 users, and every euro spent on ads was our own.

How much does each feature cost?

The more features your app needs, the more it costs, of course. That's why we always recommend building the app as lean as possible first and expanding it later.

After the prototype, you get one fixed price for all your features. Until then, this rule of thumb helps.

Low effortBuilds on data your app already has.
  • Bookmarks / favorites

    Save places, posts or conversations so you can easily get back to them later.

  • User profiles

    Personalized profiles where users manage their information, activity and personal settings in one place.

Medium effortNeeds its own logic or a service like maps or push.
  • Search and filters

    Add powerful search and filter features to your app so content, places or users are easy to find.

  • Push notifications

    Send automatic push notifications straight to your users' phones and keep them active in your app with updates, reminders or new content.

  • Interactive map

    Add a map to your app so users can easily share live locations and fixed places.

  • Events & RSVPs

    Create, discover and respond to events right in the app.

High effortReal-time features, many users at once, a separate admin panel.
  • Activity feed

    A real-time live feed for your app where users discover new content, interactions and activity from their community.

  • Event features

    Add event features to your app so users can create and discover events and manage their attendance directly.

App development with React Native and cloud technologies.

We build apps with the latest technologies to make sure your app can handle large numbers of users.

Front-end
React NativeReactNext.JS
Back-end & Infrastructure
FirebaseNode.JSSupabaseRailway
Integrations
RevenueCatStripeGoogle APIsGithub
Design & Prototyping
FigmaFigJamIllustratorAfter Effects
AI Integrations
GeminiClaudeChatGPT

Frequently asked questions about app development

How much does it cost to have an app developed?

With us, a web app starts at €10,000, a cross-platform app for iOS and Android at €20,000 and a native app at €30,000. The exact cost of your app depends on its features. After the prototype, you get a fixed price for it.

How long does it take to have an app developed?

The prototype is ready after 21 days. After that, development takes three to six months, depending on scope. You get the exact schedule on day 21, together with the fixed price.

How does it work if I want you to develop my app?

First we talk about your idea in a free call. After 21 days you click through your prototype and get the fixed price for the app. Then we build it in fixed stages and bring it to both stores. If you want, we then win the first users with you.

Why do you start with a prototype?

With the prototype, you click through your app after 21 days, before a single line of code is written. That way you see whether the app works the way you imagine it. It costs €5,490 and is fully credited when we build the app afterwards.

Web app, cross-platform or native app: what do I need?

A web app runs in the browser and costs the least. A cross-platform app reaches both stores from one codebase and is enough for most apps. We build native apps separately for iOS and Android when your app needs deep access to the device. In the first call, we tell you what fits your idea.

Can you keep developing an existing app?

Yes. We take over existing apps and software, including prototypes built with AI, and develop them into an app that runs reliably with many users.

Who owns the code and design?

You do. Code, design and all accounts are in your name. You can continue with another team at any time.

What happens after launch?

If you want, we help you get your first users in the 90 days after launch. We learned how with our own app, DeepDays.

Book your free call.

We look at your plans with you as if they were our own. If the build isn't worth it, we'll tell you, even if that means no project.

Pick a day

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