I built 25 free tools for UK freelancers — here's what I learned

A few weeks ago, I set out to build a collection of genuinely useful tools for UK freelancers — the kind of things I wished existed when I started freelancing. No sign-ups. No paywalls. No "enter your email first" gates. Just open-the-page-and-use-it tools. Here's the full list, what each one does, and what I learned building them. The tools Tax & Money Self-Employed Tax Calculator — Income tax, National Insurance, student loan, and take-home pay breakdown for 2025/26 Self-Assessment Penalty Calculator — See exactly what penalties you owe if you missed the January deadline VAT Threshold Calculator — Check if your rolling 12-month turnover means you need to register Mileage Allowance Calculator — HMRC rates for cars, vans, motorcycles, bicycles Day Rate Calculator — Work out your ideal day rate from target salary + expenses + tax Profit Margin Calculator — What you actually take home from every pound invoiced Business Expense Tracker — Track expenses by HMRC category, export CSV. Uses l