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Solo developer releases free open-source WHOOP alternative Pulsr for Apple Watch

1 article1 sourcesince Nov 2Last article 2h ago · Nov 2, 1:53 PM ET

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A solo developer says they used Claude Opus 5.5 to reverse-engineer WHOOP's features into Pulsr, a free, open-source Apple Watch and iPhone app, after canceling their $199 per year WHOOP subscription.

Pulsr computes recovery from overnight HRV, resting heart rate and sleep, a 0–21 strain score, sleep needs and a body age estimate, according to the developer's post on X.

The app includes an on-device AI coach that needs no API key. Data stays on the iPhone, and no account is required. These details come from the developer's own announcement; the report does not include independent testing of the app's accuracy.

Written by AI from the articles below · updated Nov 2, 3:08 PM ET

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Latest developmentNov 2, 1:53 PM ET

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

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Nov 2

1:53 PM
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Solo developer open-sources a free WHOOP alternative for Apple Watch
AIA 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.

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