I’ve built and shipped a number of small software projects alongside other work over the years. Some made money, some didn’t, all taught me something. Here’s an honest account of what actually works for a UK side-project software founder.
Pick Problems You Already Have
The most reliable way to build something useful is to solve a problem you live with daily. You understand the workflow without research, you can test it on yourself, and you know whether the solution genuinely works.
The opposite — building for an audience you don’t belong to — is the most common cause of side-project failure I’ve seen. You spend months building, launch, and discover the problem you imagined isn’t the problem your “target audience” actually has.
Ship in Days, Not Months
The single biggest predictor of side-project success is how quickly you get a working version in front of real users (even if those users are just you). Aim for a usable version in under a week. Anything longer and the project will compete with everything else in your life and lose.
Use Boring Technology
Side projects fail more often from over-engineering than under-engineering. Pick a stack you already know — for me, that’s Python, Flask, and Heroku. Don’t use the side project to learn three new technologies at once. Solve the problem first, optimise later.
Charge From Day One
If you intend to make money, charge from the first day. Free users give you the wrong feedback — they don’t care enough to push you on what matters. Paying users give you specific, useful pressure. Even £5/month users are different from free users.
Time Cost Reality
Side projects done seriously consume 5–15 hours a week. That’s real time taken from sleep, family, exercise, or other paid work. Plan for it honestly.
From a tax perspective, UK side-project income is taxable from £1,000/year (the trading allowance). Above that you need to declare via self-assessment. If revenue grows, registering as a sole trader is straightforward. Most side projects never reach that threshold.
Marketing Reality
Building is the easy half. Distribution is the hard half. Even a brilliant tool that solves a real problem won’t find users without intentional marketing — SEO, communities, content, paid ads, or partnerships.
Plan for at least as much time on getting users as you spent on building.
What I’d Tell My Earlier Self
- Ship the ugly version. The most painful lesson is realising you spent a month making something pretty before validating that anyone wanted it at all.
- Charge from day one. Free is its own product category and not the one you want.
- Talk to users weekly. Not surveys — actual conversations.
- Don’t hide behind the tech. Building features is comfortable; marketing is uncomfortable. Lean into the uncomfortable.
- Set a kill-switch date. If by month 3 there’s no traction, stop and try something else. Sunk cost is a trap.
Why I Mention This on a Software Developer Site
Most BuildFlow clients are running real businesses with real revenue. But occasionally I hear from someone who’s building their own software side project and wants help with one specific feature, or wants honest feedback on whether their idea is worth building. I’m happy to do that — and even happier to give you the honest answer that “build it yourself, here’s how” is sometimes the right call.
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