Solo-run Personal Best approaches $5K MRR

London developer Shaun Donnelly runs the iOS fitness app Personal Best alone while keeping part-time contract work. What began as a five-day hobby project has passed 500,000 downloads and roughly 50,000 monthly active users, with founder-reported recurring revenue approaching $5,000 a month. The app is free; Pro subscriptions and a lifetime option unlock deeper statistics, heart-rate zones, form history and unlimited goals. All processing stays on the phone with no server-side component, so Donnelly says subscription revenue has almost no marginal infrastructure cost. Acquisition comes mainly from repeated App Store features, shareable workout images, word of mouth and user support, with almost no paid marketing. The number is founder-reported; most users remain free, and pricing, conversion, refunds, platform fees and founder time are not fully disclosed.