How is an app built? A look behind the scenes

What parts is an app made of?

Most business apps consist of three parts. You only see one of them, but all three are needed:

• The app itself (the frontend): what you install on your phone. Screens, buttons, animations and everything the user touches.
• The backend: software on a server that stores data and applies rules. For example: who can see what, what an order costs, when a notification goes out.
• The admin environment: a web page where you or your team manage data, such as products, appointments or users.

The app and the backend talk to each other through an API. That is an agreed way of requesting and sending data. When you tap 'order', the app sends a message to the backend, which saves the order and sends back a confirmation.

Not every app needs its own backend. A simple calculator app or an app that only shows existing data can sometimes do without. But as soon as users log in, share data or pay, a server is almost always involved.

What technology is used to build an app?

There are three main routes. Which one fits depends on your budget, your audience and what the app needs to do:

• Native: a separate app for iPhone (usually written in Swift) and for Android (usually Kotlin). You get the most out of the phone, but there are two codebases to build and maintain.
• Cross-platform: one codebase that runs as an app on both platforms. Well-known options are React Native and Flutter. More on that in React Native or Flutter.
• Web app or PWA: an app that runs in the browser and can be added to the home screen. No app store needed. Read more about the progressive web app.

For the backend there are also plenty of choices in programming language and database. What matters most for you as the client is that it is well-known, widely used technology. That way another developer can carry on with it later.

How is an app built, step by step?

Before any code is written, the idea and the app design are usually already settled. The build then goes roughly like this:

• Setup: the developer creates the project, chooses the building blocks and prepares the environments, such as a test server and a live server.
• Data model: what data does the app store and how is it connected? Think of users, orders and products.
• Backend and API: the rules and connections are built, so the app can later fetch and save data.
• Building screens: the design is turned into working code screen by screen and connected to the backend.
• Integrations with other systems: for example payments, your accounting or a calendar.
• Testing: on different phones, screen sizes and versions of iOS and Android.
• Publishing: the app is submitted to Apple and Google, who review it before it appears in the store.

In practice these steps overlap. A good developer builds in small pieces and keeps showing you something that works along the way.

What does a week of app development look like?

Many developers work in short rounds of one or two weeks. That keeps you in control of the project:

• At the start of the round you agree which parts need to be finished.
• The developer builds and saves every change in version control. That is a system that tracks every change, so you can always go back to an earlier version.
• At the end you get a test version on your own phone. For iPhone this often goes through TestFlight, Apple's testing environment. For Android it can be done through an internal test in Google Play.
• You try out the new parts and give feedback. That goes into the next round.

The benefit: you see your app grow and can steer before too much time has gone in the wrong direction.

What happens after an app is built?

An app is never really finished. After launch, a few things carry on:

• Updates for new versions of iOS and Android, which come out every year.
• Fixing bugs that only show up once many people use the app.
• Hosting and security of the backend.
• New features based on what users ask for.

Plan for this from the start. You can read more in our article on app maintenance and updates.

Questions to ask your app developer

Now that you know how an app is built, you can ask more targeted questions when you get a quote:

• What technology do you use for the app and the backend, and why?
• Who will own the code and the Apple and Google accounts?
• How often will I see a test version?
• On which phones and versions do you test?
• What is included in maintenance after launch, and what does it cost?

Having an app built by Violexa

At Violexa we build websites and apps from design to publication. We work in short rounds, so you regularly have a test version on your own phone. We explain the technology in plain English, and you always know where the project stands.

A custom project starts from €1,799 excl. VAT (€2,177 incl. VAT). Larger apps get a fixed price up front, in writing. After launch you can choose a maintenance plan, from €179 excl. VAT (€217 incl. VAT) per month.

Want to know how your app would be built? Book a free quickscan. In 30 minutes, online or in person, we discuss your plans. Afterwards you get short written advice with a price indication, with no obligation.

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