What you need to do to build a phone app

Creating a phone app requires three things: deciding what problem your app solves, learning or hiring someone to write the code, and testing it on real phones before you release it. You do not need to be a programmer to start — many people use no-code tools that let you build without writing code at all — but you do need to understand what platform you are building for (iPhone, Android, or both), how much time and money you have, and whether you want to sell it, give it away, or make money through ads.

The path from idea to a working app in someone's pocket takes weeks to months depending on how complex your app is. A simple app with one main feature might take 4 to 8 weeks if you work alone. A more complex app with multiple features, user accounts, and data storage can take 3 to 6 months or longer. The biggest variable is not the idea — it is whether you are writing the code yourself, paying a developer, or using a tool that does some of the work for you.

Key Takeaways

  • Decide whether you are building for iPhone (iOS), Android, or both, because the tools and languages are different for each platform.
  • You can build without coding using no-code platforms like Flutterflow or Bubble, or you can learn a programming language like Swift (iOS) or Kotlin (Android).
  • Test your app on real phones, not just in a simulator, because real devices behave differently and users will notice bugs that the simulator misses.
  • Before you start coding, write down what your app does, who uses it, and what screens or features it needs — this plan saves time and money later.
  • You will need to pay a fee to publish your app on the Apple App Store or Google Play Store, and both stores review your app before it goes live.

Choose your platform: iOS, Android, or both

iPhone apps run on iOS and Android apps run on Android phones. The two platforms use different programming languages, different design rules, and different app stores. If you build for iOS only, you reach iPhone users. If you build for Android only, you reach Samsung, Google Pixel, and other Android phone users. If you build for both, you reach everyone, but it takes longer and costs more.

Most people starting out choose one platform first. iOS apps are often easier to publish because Apple reviews apps more strictly but the process is more straightforward. Android has more phones in the world but the devices vary widely in screen size and power. If your target users are mostly in North America or Europe, iOS is a reasonable starting point. If your users are worldwide or in developing countries, Android reaches more people.

You can also build a web app that works in a phone's browser instead of being installed like a traditional app. Web apps are faster to build and work on any phone, but they cannot access some phone features like the camera or location as easily, and users have to visit a website instead of tapping an icon on their home screen.

Decide whether to code or use a no-code tool

If you know how to code or want to learn, you can write the app yourself. For iOS, you learn Swift and use Apple's Xcode tool. For Android, you learn Kotlin and use Android Studio. Both are free to download. Learning either language takes weeks to months depending on your background, and you will spend time debugging (finding and fixing mistakes) before your app works.

If you do not want to learn to code, no-code platforms let you build an app by dragging components onto a screen and connecting them with logic. Popular no-code tools include Flutterflow (builds for both iOS and Android), Bubble (web apps and mobile apps), Adalo, and MIT App Inventor (free, simpler, good for learning). These tools are faster — you can have a working prototype in days — but they are less flexible. If your app needs something unusual, a no-code tool might not do it.

A third option is to hire a developer. Freelance developers on platforms like Upwork or Toptal charge anywhere from $25 to $150 per hour depending on experience and location. A simple app might cost $5,000 to $15,000. A more complex app can cost $30,000 to $100,000 or more. This is the fastest path if you have money but not time or coding skills.

Plan your app before you start building

Before you write any code or open a no-code tool, spend time writing down what your app does. List the main features, the screens the user will see, and what happens when they tap a button. This document is called a wireframe or specification. It does not have to be fancy — pen and paper works, or you can use free tools like Figma or Balsamiq to draw it.

Write down who your app is for. Are they teenagers, parents, small business owners, or someone else? What problem does your app solve for them? What do they do most often in your app? This clarity saves you from building features nobody wants and helps you decide what to build first.

Decide what data your app needs to store. Does it need user accounts? Does it save information to the cloud so the user can access it on another phone? Does it work offline? These decisions affect how long the app takes to build and how much it costs to run.

Build, test, and fix on real phones

Once you start building, test your app constantly on real phones, not just in a simulator on your computer. Simulators are useful for quick checks, but real phones have different screen sizes, different speeds, and different versions of iOS or Android. A button that looks fine in the simulator might be too small to tap on a real phone. An animation that runs smoothly in the simulator might stutter on an older phone.

Ask friends and family to use your app and tell you what breaks. Watch them use it without telling them what to do — you will see mistakes you did not expect. Fix the most important bugs first: crashes, features that do not work at all, and things that are confusing. Small visual bugs can wait.

Test on at least two different phones if you can — one newer and one older. Test on different versions of iOS or Android. Test with a slow internet connection. Test what happens when the app loses connection and gets it back. These edge cases are where most bugs hide.

Publish to the App Store or Google Play

To publish an iOS app, you need an Apple Developer account, which costs $99 per year. To publish an Android app, you need a Google Play Developer account, which costs $25 one time. Both require you to provide information about your app, screenshots, a description, and your contact details.

Apple reviews every app before it goes live, which takes 24 hours to a few days. Apple checks that your app does what it says it does, that it does not crash, and that it follows Apple's design rules. If Apple rejects your app, they tell you why and you can fix it and resubmit.

Google Play also reviews apps, but the process is usually faster. Most apps are approved within a few hours. Google checks similar things: that the app works, that it is not malware, and that it follows Google's rules.

Once your app is published, you can update it. Users get a notification that an update is available and can download it. You can fix bugs, add features, and improve the design without paying another fee.

Decide how to make money (or keep it free)

You have several options for making money from your app. You can charge users upfront — they pay $0.99, $4.99, or whatever you choose to download it. You can offer it free and show ads inside the app using a service like Google AdMob. You can offer a free version with limited features and charge for a "pro" version with more features. You can offer the app free but charge for things inside it — extra levels in a game, premium content, or removing ads.

Most successful apps use a combination: free to download, with ads or in-app purchases to make money. Charging upfront works only if your app solves a real problem people are willing to pay for. Games and entertainment apps often use ads or in-app purchases. Productivity and utility apps often charge upfront or have a free version with a paid upgrade.

Frequently Asked Questions

How long does it take to learn to code an app?

Learning the basics of Swift or Kotlin takes 2 to 4 months if you study regularly. Building your first simple app takes another 4 to 8 weeks. If you have no programming experience at all, add another month to learn programming fundamentals first. Using a no-code tool is much faster — you can build a working prototype in days.

Can I build an app for both iPhone and Android at the same time?

Yes, but it takes longer. You can use a framework like React Native or Flutter that lets you write code once and run it on both platforms. These frameworks are faster than coding iOS and Android separately, but they require learning a new language and have some limitations. No-code tools like Flutterflow also build for both platforms at once.

What if my app idea already exists?

Most successful apps have competitors. What matters is whether your version is better, cheaper, faster, or solves the problem in a way people prefer. Study what the existing apps do well and what they do poorly. Build something that fixes the problems or adds features people want. Many apps succeed even though similar apps already exist.

Do I need a business license to publish an app?

It depends on where you live and whether you are making money. If you are building a free app as a hobby, you probably do not need a license. If you are charging money or showing ads, check your local laws — most places require some form of business registration if you are earning income. Talk to a local business advisor or accountant to be sure.

What happens if my app crashes after I publish it?

You can push an update to fix it. Users will see a notification that an update is available, and they can download it. You do not have to wait for the app store to review it again unless you are adding new features or changing how the app works fundamentally. Bug fixes usually go live within hours.