Deciding What to Build

Why do you want to build an app?

The first thing to work out is what you want from the project, because that changes which ideas are worth pursuing. I think there are three good reasons to build something:

1. Fun. Building is fun. Sometimes you just want to see whether you can make an idea work.
2. Money. Money is nice. You might want a side income, or you might want to build a business.
3. To help someone. You've noticed a problem and think you can do something about it.

They can overlap. You can enjoy building something useful and get paid for it.

If you're building for fun, you don't need to turn it into a business exercise. If you want people to pay for it, though, there are a few more questions worth asking.

If you want to make money

Alex Hormozi has a useful framework for choosing a market in his teaching around $100M Offers. He looks for four things. ^[1]

• A painful problem. It matters enough that people want it solved. It's costing them something: time, money, frustration or a missed opportunity.
• Purchasing power. The people who need your solution have the money, or access to the budget, to pay for it.
• People you can reach. You can identify your target customers and find them through particular communities, channels or organisations.
• A growing market. You're looking at a market that's expanding rather than shrinking.

You could have a clever idea and still struggle because the people who need it can't pay, or because you have no practical way to reach them. These questions help you think about that before you've spent months building. They don't prove that your particular idea will sell.

Get more than a polite nod

When I first wanted to become an entrepreneur, I told people I was going to build a clothing brand. I got plenty of encouragement, but I always had a feeling that people were just being nice.

Pitch friends and family your next million-pound business idea and you'll probably recognise that feeling. The polite nod doesn't tell you whether someone has the problem, how much it matters, or whether they'd pay to solve it.

That's why I like The Mom Test by Rob Fitzpatrick. It teaches you to ask questions that produce useful information even when the other person wants to encourage you. The trick is to talk about their life and what they've actually done, rather than asking them to predict whether they'd use your idea. ^[2]

For example, if you're thinking about an app for personal trainers:

Then listen. Maybe cancellations are a nightmare. Maybe their existing tools already handle them perfectly. Either answer is useful.

You have to detach your ego from the idea a little. Finding out that people don't have the problem you imagined can save you a lot of time.

Later, when you have something specific to offer, a real commitment, such as agreeing to a paid pilot, tells you more than “sounds great.” If target customers are willing to pay before you've built it, you may be onto something. It still isn't a guarantee, but it's better evidence than encouragement. ^[2]

Check the rules early

Find out which rules could affect your app while you're still choosing what to build. For a mobile app, start with the store's review guidelines. Apple has rules about copycats, minimum functionality and spam, including apps that are indistinguishable from widely available offerings. Giving an existing app a new name and colour scheme may not get you very far. ^[3]

That doesn't mean every idea has to invent a completely new category. It does mean reading the relevant store's requirements before you commit to building, and remembering that meeting an individual guideline doesn't guarantee approval.

Platform rules are only part of it. If your idea involves an industry with a lot of regulation, such as pharmaceuticals or medical services, find out which regulations apply as well.

Decide what success means to you

One more book I'd recommend is Anything You Want by Derek Sivers, the founder of CD Baby. He encourages you to think about how you measure success, instead of automatically adopting somebody else's definition. ^[4]

For you, success might be learning a new skill, helping a small group of people, or earning enough to make the project worth continuing. You don't have to aim for the biggest possible business just because somebody else does.

Before you give an idea months of your life, write down what you want from it. If money is part of the answer, find one person who might have the problem and ask what happened the last time they dealt with it.

If you'd like to learn how an app gets built before you commit to your own idea, Getting Started with Coding Agents builds and publishes a small reading-list app with Claude Code or Codex in ten parts. It needs no coding experience.

Books & sources

These are the books and original sources behind the ideas above. The book links go to Amazon UK and aren't affiliate links.

1. Alex Hormozi — $100M Offers. For thinking about your market and offer. Find the book on Amazon UK.
2. Rob Fitzpatrick — The Mom Test. For having customer conversations you can actually learn from. Find the book on Amazon UK.
3. Apple — App Review Guidelines. Start with 4.1 Copycats, 4.2 Minimum Functionality and 4.3 Spam. Apple revises these guidelines, so read the current version when planning your app.
4. Derek Sivers — Anything You Want. For deciding what you want your business to be. Find the book on Amazon UK.