Personal Best

What makes it different

Personal Best is a workout-tracking app for iPhone, iPad, and Apple Watch. It started in May 2020 as a five-day hobby project during the COVID lockdowns — founder Shaun Donnelly, a London software engineer, only meant to ship a basic v1.0, but enjoyed building it so much he kept going. Five years later it has over 500,000 downloads and about 50,000 monthly active users, has been featured on the App Store multiple times, and made a cameo in the WWDC 2026 keynote.

In the founder's own words: 'I'm close to $5K MRR.' The economics are indie-perfect — Personal Best has no server-side component, so the app runs entirely on the phone and every Pro subscription is almost 100% profit, with virtually no marginal costs. Pro, introduced in late 2020, offers extra stats, heart-rate zones, unlimited goals, and a lifetime option.

The growth story is slow-burn organic: almost no paid marketing, just years of App Store featuring, a product-led image-sharing feature (turn workouts into editorial-quality images to post on social), and a founder who freelances part-time to fund full-time indie work. Donnelly has left X behind and now posts on Mastodon and his blog at codakuma.com.

The playbook, in their own words

• Started May 2020 as a ~5-day hobby project during the COVID lockdowns — a quick v1.0 he kept improving because he enjoyed building it source ↗
• Grew to 500,000+ downloads and ~50,000 monthly active users; featured on the App Store multiple times; made a cameo in the WWDC 2026 keynote source ↗
• Almost no paid marketing — purely organic growth that picked up once Apple began featuring the app source ↗
• No server-side component: the app runs entirely on the phone, so every subscription is almost 100% profit with virtually no marginal cost source ↗
• Product-led growth via workout image-sharing — turn workouts into editorial-quality images to post on social source ↗