Joel Farthing

Joel Farthing

Filament Labs: A Window, not a Verdict
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About

Tools for the data-curious. Currently building HRVSpark — raw HRV sparklines on your wrist.

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Maker History

  • HRVSpark
    HRVSparkYour HRV. Raw. Beautiful. On your wrist.
    Mar 2026
    • 🎉
    Joined Product HuntMarch 3rd, 2026

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Joel Farthing•

2mo ago

HRVSpark - Your HRV. Raw. Beautiful. On your wrist.

The usual HRV app flow: data → algorithm → verdict → user. HRVSpark reverses it: data → user → intuition. Raw SDNN sparklines and gauges on your Apple Watch face, across four time windows. Complication-first — always visible, never buried in an app. Works alongside analysis suites like Athlytic or HRV4Training, or stands alone as your only HRV tool. $2.99 one-time. No subscription. No account.
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