# Solo developer open-sources a free WHOOP alternative for Apple Watch

> Original title: I just canceled my $199 / year WHOOP subscription, and…

- Source: X search: indie AI launches (I built, solo founder)
- Published: 2026-11-02T18:53:21.000Z
- Bad Influence: https://badinfluence.news/items/e1742tpvfuwdvqf63qea2vec5
- Original: https://x.com/0xCodez/status/2117329233110507981

## Summary

A developer says they canceled their $199 per year WHOOP subscription and used Opus 5.5 to reverse-engineer the app into Pulsr, an open-source Apple Watch and iPhone app. Pulsr computes recovery from overnight HRV, resting heart rate and sleep, a 0–21 strain score, sleep needs and a body age estimate. It includes an on-device AI coach that needs no API key, and it stores data only on the iPhone with no account required.

## Post

I just canceled my $199 / year WHOOP subscription, and…

reverse-engineered their entire app for my Apple Watch with Opus 5.5 in 2 hours, then i made it open-source:

→ https://github.com/0xCodez/pulsr

recovery. strain. sleep. one beating orb. free and open-source.

what it does:

→ Recovery 0–100% from your overnight HRV, resting heart rate and sleep
→ Strain 0-21 with a daily target based on your recovery
→ how much sleep you need tonight + a recommended bedtime
→ stress monitor, health monitor and a “body age” estimate
→ a journal that shows which habits help or hurt your recovery
→ an AI coach that runs on-device. no API key
→ an Apple Watch app, light and dark mode
→ no subscription, no account. your data never leaves your iPhone

Find full prompt below ↓

Then, read how to rebuild any app from scratch with Opus 5.5 in the article below.

[Video](https://badinfluence.news/api/img-proxy?u=https%3A%2F%2Fpbs.twimg.com%2Famplify_video_thumb%2F2117329089782587392%2Fimg%2FWvRbg5gjg5wfbllM.jpg&mode=thumb&exp=1793836800&sig=9c1198a5651e451a)

## Quoted post @0xMovez

> https://x.com/i/article/2109583646684315648

https://x.com/0xMovez/status/2109604520770548146