Launched this week
HRVSpark
Your HRV. Raw. Beautiful. On your wrist.
5 followers
Your HRV. Raw. Beautiful. On your wrist.
5 followers
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.
Hey 👋 I'm Joel, solo dev behind HRVSpark.
I built this because I have AFib and anxiety, which lead me to pay close attention to my Heart Rate Variability. I like some of the interpretive apps. But I noticed a pattern: open the HRV app, see a readiness score, spiral a little. Was that score low because of a real problem, or because I slept weird? I appreciate what the algorithmic apps do — they're genuinely useful for a lot of people — but they never clicked for me the way the granular data does.
So I stopped looking at scores and started looking at the numbers buried in HealthKit. I noticed my own patterns — HRV crashes after yoga, spikes after cold plunges, a slow drift upward while sleeping. I didn't need an algorithm to tell me those things. I just needed to see them.
The 8-hour raw sparkline complication is the one I originally made for myself — it's the view I check a dozen times a day. And it's one of the free ones. I wanted anyone with anxiety or an arrhythmia to be able to see exactly how their interventions affect the actual numbers, without paying for the privilege.
HRVSpark puts your raw SDNN values on your Apple Watch face as live sparklines and gauges. No scores, no colors, no stress labels. Just your HealthKit data, always visible, across four time windows.
The hero window is free. $2.99 one-time Pro unlock. No subscription. No account.
I'd genuinely love to hear:
- Do you find the "no-scores" approach freeing or unsettling?
- Which complications do you actually use on your watch face?
- Is there a time window you wish we had?