Ask HN: Good Fitness Band?

I recently got the flu and was thinking it would be interesting to have a graph of my body temperature, which made me consider buying a fitness band. Are there any that HN likes?

  Factors I care about:
  - Slim design and good battery life
  - No subscription required to unlock any features
  - Lots of interesting sensors (heart rate, SpO2, skin temp, pedometer, others?)
  - Open data access, reverse engineered APIs, 3rd party data analysis apps

Happy holidays!

I've been generally disappointed with my Apple Watch, though it looks good and the fitness tracking app mostly works as intended. I find the interface buggy and slow and you can never use it more than a day in a row without charging.

Prob not fitting your criteria but the Withings band does interesting things like detect when my night time heart beat is high and reasonably guesses that I have a fever. Which I do. I have the BP monitor and scales as well and they work well together but it's the band that as seems to reveal the most insights.

I'd love to hear if anyone has suggestions with an additional feature:

- No internet access / sign up / data syncing to the cloud is required (ideally it wouldn't exist at all). The ideal would be connecting the device directly to a computer via USB or bluetooth and pulling the data / logs off of it directly.

Combined with open data access / reverse engineering this would be very powerful. Basically I want a band where it is impossible for anyone besides me to get access to my data (without physically stealing the band or hacking my computer).

I used to have a FitBit that I wasn't entirely happy with. After some health issues, I recently upgraded to a FitBit Charge 5 that I'm mostly satisfied with. It was quite inexpensive; I got mine for $99. It does continuous heart rate monitoring, but I have doubts about the accuracy of its resting heart rate calculation. It has all of the "interesting sensors" you listed, but I haven't explored them all. The one feature that decided me was the ElectroCardioGram (ECG) function. It's not perfect. It requires that you sit very still for 30 seconds with thumb and forefinger grasping the sides of the FitBit, and it only checks for A-Fib (Atrial fibrillation), but there aren't that many fitness bands that have that function, and it was important to me to get one with that feature.

My biggest disappointment with this band is the sleep tracking (which was also a failing with my previous FitBit). I have to get up at 7:30 to feed my cat, then I go back to bed for an hour or so. Both my old and my new FitBit record 7:30 as the end of my sleep period; they ignore the sleep time after 7:30. I'm also not convinced that a band you wear on your wrist can accurately track REM sleep.

I use the FitBit app for some other features and controls, but I have no idea about "Open data access, reverse engineered APIs, 3rd party data analysis apps".

All in all, I'm happy with my FitBit Charge 5, and I think it's a good value for its price.