Raw heart-rate variability
hrv/spark
Your HRV as a live Apple Watch sparkline, without readiness scores, stress labels, or algorithmic verdicts. A clear view of HealthKit SDNN values across useful time windows.
Independent software from Fayetteville, Arkansas
Filament Labs
A window, not a verdict.
We build privacy-first tools for people who already bring their own intelligence to the data. No accounts. No telemetry. No interpretation layer pretending to know you better than you know yourself.
Product posture
0
Telemetry
Health data stays under your control.
0
Accounts
No login to see your own data.
2
Watch Tools
HRV and resting heart-rate signals.
1
Principle
Show the signal. Trust the person.
Current tools
Small instruments for people who notice patterns.
HRVSpark and RHRSpark are Apple Watch health tools with the same bias: keep the data close, keep the presentation calm, and leave the final meaning with the person wearing the watch.
Transparent resting heart rate
rhr/spark
Sedentary heart-rate trends and Apple's daily RHR on your watch face, clearly labeled and never blended into a mystery metric.
Why this exists
Software should respect the person using it.
Filament Labs is the independent work of a solo developer building tools that are small on purpose: focused, private, and honest about what they know.
The health tools here are not designed to grade your body, manufacture urgency, or keep you checking. They are designed to make a signal easier to see, then get out of the way.