What you need to build an app

Building an app requires three things: a clear idea of what problem it solves, a choice of platform (iOS, Android, or web), and either coding skills or money to hire someone who has them. You do not need a computer science degree, but you do need to understand that apps take weeks or months to build, cost money at multiple stages, and often need ongoing maintenance after launch.

Most people start by choosing between native apps (built specifically for iPhone or Android) and cross-platform frameworks (code once, run on both). Native apps perform better and feel more natural to users, but take longer to build twice. Cross-platform tools like React Native or Flutter let you write one codebase that runs on both systems, which saves time but sometimes sacrifices performance or features.

The other major choice is whether to code it yourself, hire a freelancer, or work with an agency. Self-coding takes the longest but costs almost nothing upfront. Freelancers cost $5,000 to $50,000 depending on complexity. Agencies cost $50,000 and up and handle everything from design to launch, but you lose control over the process.

Key Takeaways

  • Decide what problem your app solves and who will use it before you write any code or spend money on design.
  • Choose between iOS, Android, or web based on where your users are — most people need both iOS and Android, which means either building twice or using a cross-platform tool.
  • Self-coding requires learning a programming language and takes months; hiring a freelancer costs $5,000 to $50,000; agencies cost $50,000 and up but handle the whole process.
  • Plan for ongoing costs after launch: server fees, app store fees, bug fixes, and updates to keep the app working as operating systems change.

Define your idea and validate it first

Before you build anything, write down exactly what your app does, who needs it, and why they would use it instead of existing options. This is not a business plan — it is a single page describing the core feature, the user, and the problem it solves. An example: "A timer app for people doing the Pomodoro technique that syncs across their phone and laptop."

Talk to at least five people who would actually use the app and ask them whether they would pay for it or use it if it were free. If they say yes but do not seem excited, that is a warning sign. If they say they would use it but never actually do when you show them a prototype, that is a bigger warning. This step saves you months of building something nobody wants.

Sketch the app on paper or in a free tool like Figma. Draw the main screens, the buttons, and the flow from one screen to the next. This takes a few hours and catches design problems before you write code. Show the sketches to the same five people and ask whether they understand how to use it.

Choose your platform and technology

iOS and Android together cover over 99 percent of smartphones worldwide, but they require different code. If you are coding yourself, you have three paths: learn Swift for iOS only, learn Kotlin for Android only, or learn a cross-platform framework like React Native or Flutter that lets you write one codebase for both.

React Native uses JavaScript and is the most popular cross-platform choice. It powers apps like Discord and Shopify. Flutter uses a language called Dart and is newer but growing fast; it powers Google's own apps. Both are free and have large communities. The trade-off is that cross-platform apps sometimes cannot access newer phone features as quickly as native apps can, and they may feel slightly slower on older phones.

Web apps run in a browser and work on any device without installation. They are faster to build than mobile apps and cost less to maintain, but users have to visit a website instead of tapping an icon. Many companies start with a web app and add mobile apps later.

If you are hiring someone, ask them which platform they specialize in. A developer who knows React Native well will build faster and cheaper than one learning it for your project.

Learn to code or hire someone

If you want to code it yourself, start with free resources. Codecademy, freeCodeCamp, and Udemy have courses in JavaScript, Swift, Kotlin, and Flutter. Budget three to six months of part-time work to learn enough to build a simple app. Your first app will take longer than you expect — plan for six months to a year if you are learning as you go.

If you hire a freelancer, post your project on Upwork, Toptal, or Fiverr with your sketches and description. Ask for a fixed price, not hourly rates, so you know the total cost upfront. Request a timeline and ask for weekly updates. Check their portfolio for apps similar to yours. A simple app might cost $5,000 to $15,000; a complex one with user accounts, payments, and a backend server costs $30,000 to $100,000.

Agencies handle design, development, and testing all at once. They cost more but move faster and take responsibility for quality. Expect to pay $50,000 to $200,000 and wait three to six months. Use an agency if you have funding or if the app is critical to your business.

Design and build the app

Design comes before coding. A designer creates mockups of every screen, showing exactly how buttons look, where text goes, and how the app responds when you tap something. This takes two to four weeks and costs $2,000 to $10,000 if you hire someone, or is free if you do it yourself in Figma.

Once design is done, development begins. The developer builds the user interface (what you see), the logic (what happens when you tap a button), and the backend (servers that store data if your app needs them). A simple app with no backend takes four to eight weeks. An app with user accounts, payments, or a database takes two to four months.

During development, ask for a working version every two weeks so you can test it and give feedback. Changes are cheaper to make early. Once the app is feature-complete, testing begins — the developer or a tester tries every button, every screen, and every edge case to find bugs.

Prepare for launch and ongoing costs

Before you launch, you need accounts with Apple and Google. Apple charges $99 per year to publish on the App Store. Google charges $25 once to publish on Google Play. Both review your app before it goes live — this takes three to seven days and they may reject it if it breaks their rules.

If your app stores data or handles payments, you need a server. Services like Firebase (free for small apps, then $25 to $100 per month as you grow) or AWS (pay for what you use, typically $10 to $100 per month starting out) handle this. You also need a privacy policy and terms of service, which you can generate free from sites like Termly.

After launch, plan for ongoing work. Operating systems change every year, and your app needs updates to keep working. Bug fixes come up. Users request features. Budget $500 to $2,000 per month for maintenance, or hire a developer part-time at $1,000 to $3,000 per month.

Market your app after launch

Launching the app is not the end — it is the beginning of getting people to download it. App stores have millions of apps, so yours will not be found unless you tell people about it. The cheapest way is to tell friends, post on social media, and ask early users to leave reviews (reviews improve your ranking in the app store).

Paid advertising through Google Ads or Apple Search Ads costs $500 to $5,000 per month depending on how many downloads you want. Press coverage is free but hard to get unless your app solves a problem journalists care about. Many successful apps grew through word of mouth — one person told another, who told another.

Track how many people download your app, how many use it regularly, and where they came from. This tells you whether your marketing is working and where to spend more money. Tools like Firebase Analytics (free) or Mixpanel (free for small apps) do this automatically.

Frequently Asked Questions

How long does it take to build an app?

A simple app with one or two screens takes four to eight weeks if you hire a developer. A complex app with user accounts, payments, and a backend takes three to six months. If you are learning to code as you go, add three to six months more. The timeline depends on how many features you want and how many people are working on it.

How much does it cost to build an app?

A simple app costs $5,000 to $15,000 if you hire a freelancer, or free if you code it yourself (plus your time). A complex app costs $30,000 to $100,000 with a freelancer or $50,000 to $200,000 with an agency. Add $99 per year for Apple and $25 once for Google, plus $10 to $100 per month for servers if your app stores data.

Should I build for iOS or Android first?

If you have limited budget, pick the platform your users are most likely to have. In the US, more people use iPhone; worldwide, more people use Android. If you cannot decide, use a cross-platform tool like React Native or Flutter so you can launch on both at once. Many successful apps launched on one platform first and added the other later.

Do I need to know how to code to build an app?

No. You can hire a developer or use a no-code tool like Flutterflow or Bubble that lets you build an app by dragging and dropping instead of writing code. No-code tools are slower for complex apps but work well for simple ones and cost less than hiring a developer.

What happens after I launch my app?

You need to maintain it — fix bugs, update it when iOS and Android change, and add features users request. Plan to spend $500 to $2,000 per month on maintenance, or hire a part-time developer. You also need to market it so people know it exists and download it.