You need three things: a clear idea of what the app does, a way to build it, and a plan for getting it in front of users
Building a mobile app starts with deciding what problem it solves and who will use it. Then you pick a path: hire a developer, learn to code yourself, use a no-code platform, or work with an agency. Each path costs different amounts of time and money. The app then goes through design, building the actual code, testing, and finally submission to Apple's App Store or Google Play. Most people underestimate how long testing takes and how much work happens after launch.
This guide walks you through each stage so you understand what you are signing up for, what questions to ask if you hire someone, and where most projects get stuck.
Key Takeaways
- Start by writing down exactly what your app does, who uses it, and what problem it solves — this document saves money later because developers will not have to guess.
- You have four main paths: hire a developer (most expensive, most control), learn to code (slowest, cheapest), use a no-code platform (fastest for straightforward apps, limited for complex ones), or hire an agency (most expensive, least hands-on for you).
- The actual building phase is only about 30 percent of the work — design, testing, bug fixes, and getting approval from app stores take the rest of the time.
- Apple and Google both review apps before they go live, and rejections happen for reasons you cannot see coming, so budget extra time before your launch date.
- After launch, you will spend money on server costs, updates for new phone operating systems, and fixing bugs that users find.
Start with a written description of what your app actually does
Before you spend money or time, write down what your app does in one paragraph. Include: what problem it solves, who uses it, what they do inside the app, and what makes it different from apps that already exist. This is not a business plan. It is a one-page document that a developer can read and say "I understand what you want to build."
Include specific examples. Instead of "users can share photos," write "users can upload a photo from their phone, add a caption, and send it to one person or a group." Instead of "the app tracks fitness," write "the app records how many steps the user took today and shows them a graph of the last seven days." Vague descriptions lead to developers building the wrong thing, which costs you time and money to fix.
Also list what the app does not do. If your app is for scheduling appointments but does not handle payments, say that. If it works only on iPhones at first, say that. This prevents misunderstandings later.
Choose how you will build the app: four main paths
The path you pick depends on your budget, timeline, and how much control you want.
| Path | Cost | Timeline | Best for | Biggest drawback |
|---|---|---|---|---|
| Hire a freelance developer | $5,000 to $50,000 | 2 to 6 months | straightforward apps, small budgets | Quality varies widely; you manage the project yourself |
| Learn to code and build it yourself | $0 to $2,000 (courses) | 6 months to 2 years | You have time and want to learn | Takes much longer than you think; you are responsible for everything |
| Use a no-code platform | $50 to $500 per month | 1 to 3 months | straightforward apps, fast launch, low budget | Limited features; you cannot customize deeply |
| Hire an agency | $50,000 to $500,000+ | 3 to 12 months | Complex apps, large budgets, hands-off approach | Most expensive; less direct control over decisions |
Freelance developers are individuals you find on platforms like Upwork, Toptal, or through referrals. You pay them per project or hourly. The advantage is low cost and flexibility. The disadvantage is that you have to manage the project yourself — you decide what gets built each week, you catch mistakes, and if the developer disappears, you have limited recourse. Ask for references and look at apps they have actually shipped, not just portfolio pieces.
Learning to code yourself means taking courses in Swift (for iPhone apps) or Kotlin (for Android apps), or learning a cross-platform language like React Native or Flutter. Free resources exist on YouTube and through platforms like Codecademy. This path is cheapest but slowest. Most people who start this way underestimate how long it takes — building a straightforward app takes six months to a year if you work part-time. You also have to learn not just coding but design, testing, and how to submit to app stores.
No-code platforms like FlutterFlow, Bubble, or Adalo let you build an app by dragging components around instead of writing code. You pay a monthly subscription. This works well for straightforward apps: a to-do list, a local business directory, a straightforward game. It does not work for apps that need complex logic, custom animations, or deep integration with phone hardware like the camera or location services. The app you build is also limited to what the platform allows — you cannot customize it beyond that.
Agencies are companies with teams of designers, developers, and project managers. They handle everything from start to finish. You pay the most but do the least work. This makes sense if your app is complex, your budget is large, or you do not have time to manage a freelancer. The trade-off is that you have less day-to-day control and less visibility into what is happening.
The actual building process: design, code, test, submit
Once you have chosen your path, the app goes through four phases. Most people think building the code is the longest phase. It is not.
Design (2 to 8 weeks) means creating mockups of what each screen looks like, how buttons are arranged, what colors and fonts are used, and how a user moves from one screen to the next. A designer creates these mockups in tools like Figma or Adobe XD. If you are using a no-code platform or building it yourself, you might skip formal design and start building directly, but this usually costs you time later because you have to rebuild screens that do not work well.
Building the code (4 to 16 weeks) is when the developer writes the actual code that makes the app work. If the app needs a backend — a server that stores data, handles user accounts, or processes payments — that gets built at the same time. This is the phase people think takes the longest, but it usually does not. A straightforward app might take four weeks. A complex app with lots of features might take four months.
Testing (2 to 8 weeks) means checking that every button works, every screen loads, and the app does not crash. This includes testing on different phone models, different versions of iOS or Android, and different internet speeds. Testing also means checking that the app works the way you described it in your original document. If the developer built something different, this is when you catch it. Testing takes longer than people expect because bugs hide in unexpected places.
Submission and review (1 to 4 weeks) means uploading your app to the Apple App Store and Google Play Store. Both companies review the app before it goes live. Apple's review usually takes 24 to 48 hours but can take longer if they have questions. Google's review usually takes a few hours to a few days. If the reviewers find a problem — the app crashes, it does not do what the description says, or it violates their rules — they reject it and you have to fix it and resubmit. This can add weeks to your timeline.
What happens after your app launches
Launch is not the end. It is the beginning of ongoing work.
Server and hosting costs start when ready if your app stores data in the cloud. A straightforward app might cost $10 to $50 per month. A popular app with millions of users might cost thousands per month. These costs grow as your user base grows.
Operating system updates happen twice a year. Apple releases a new version of iOS, and Google releases a new version of Android. Your app has to be updated to work with these new versions, or it will stop working or get removed from the app stores. This usually takes a few weeks of work per update.
Bug fixes happen constantly. Users will find problems that your testing did not catch. You have to fix these and push out new versions. How often you update depends on how many bugs users find and how serious they are.
New features are optional but common. Users will ask for things your app does not do. You decide which requests to build and which to ignore. Each new feature adds cost and timeline.
Questions to ask before you hire someone to build your app
If you are hiring a developer or agency, ask these questions before you sign a contract:
- Will the app work on both iPhone and Android, or just one? Building for both costs more and takes longer than building for one. Some developers specialize in one platform.
- Who owns the code after I pay you? You want to own the code so you can hire someone else to maintain it later. Some developers or agencies keep ownership, which locks you in.
- What happens if you disappear or go out of business? Ask how you get access to the code and the server if the developer stops responding. Get this in writing.
- How much will updates and bug fixes cost after launch? Do not assume they are free. Get a number in writing.
- Can I see apps you have actually shipped to the App Store or Google Play? Portfolio pieces do not count. You want to see real apps that real users use.
- How do you handle scope creep? Scope creep means you ask for more features than you originally agreed to. Ask how the developer handles this — do they charge extra, or is it included?
Common reasons apps get rejected by Apple and Google
Apple and Google both have rules about what apps can do. If your app breaks these rules, it gets rejected and you have to fix it before it can launch. Budget extra time for this.
Common rejection reasons include: the app crashes when you use it, the app does not do what the description says it does, the app asks for permissions it does not need (like access to your contacts when it is just a calculator), the app has bugs that make it unusable, or the app violates the store's policies on content, privacy, or behavior. Apple is stricter than Google. If your app is rejected by Apple, you usually get a message explaining why, but sometimes the explanation is vague and you have to guess what they want.
To avoid rejection, test your app thoroughly before you submit it, make sure the description matches what the app actually does, and review the App Store and Google Play policies before you build. If you are unsure whether your app will be allowed, ask the store directly before you build it.
Frequently Asked Questions
How much does it cost to build a mobile app?
A straightforward app built by a freelancer costs $5,000 to $15,000. A moderately complex app costs $25,000 to $75,000. A complex app or one built by an agency costs $100,000 to $500,000 or more. No-code platforms cost $50 to $500 per month. Building it yourself costs almost nothing upfront but costs your time.
How long does it take to build a mobile app?
A straightforward app takes two to four months from start to launch. A moderately complex app takes four to eight months. A very complex app takes a year or more. These timelines assume you have a clear description of what you want, you make decisions quickly, and the app does not get rejected by the app stores. If any of those things are not true, add more time.
Do I need to know how to code to build an app?
No. You can hire a developer, use a no-code platform, or work with an agency. You do need to know what you want the app to do and be able to describe it clearly. The clearer your description, the better the app will be and the less it will cost.
What is the difference between iOS and Android?
iOS is Apple's operating system for iPhones and iPads. Android is Google's operating system for most other phones. Apps built for iOS do not work on Android and vice versa. Building for both means building the app twice, which costs more and takes longer. Some developers use cross-platform tools like React Native that let them build once and run on both, but this approach has trade-offs in performance and customization.
What happens if my app idea already exists?
Many app ideas already exist. That is okay. You can still build your version if you think you can do it better, faster, cheaper, or for a different audience. Look at the existing apps, understand what they do well and what they do poorly, and build something that addresses the gaps. Do not copy their code or design — that is illegal — but you can learn from how they work.