I would like to buy fitness trackers for me and my family (my father and mother (77/79), me (50) and my son (7 yo). We would like to compare data in the internet, not just one-by-one on a smartphone each. Is there any fitness tracker, which can put data to the internet? How is data transferred? My father and I have an Android smartphone each. We would like to have pulse, some activity and sleep data. Which fitness tracker could be used? How is data transferred to the internet (via smartphone?)? On which internet site can we see the data? Is there any site, where you can compare data of a group of people? (We all live in Germany, my paratents together and we (my wife doesn’t want to participate)
I would recommend one of the following: Fitbit, Garmin, or Withings.
All of them have websites where you can see your data, and all of them track pulse, activity, and sleep. They all have affordable options and great developer APIs that make it easy to access your data.
I excluded Apple, Samsung, Whoop, and Oura because they either don’t make it easy to access your data, don’t have affordable options, or aren’t appropriate for all the age ranges you mentioned.
I personally think that Garmin makes the best fitness devices, but in this case I would recommend going with Fitbit because it will be appropriate for all the age ranges you mentioned.
For your son: Fitbit Ace or Inspire
For you/your parents: Fitbit Inspire, Charge, or Versa
Mi band 3 is the cheapest option I know of. It should fulfill most of your requirements though the pulse rate tracker is not too good like, I imagine, in most bands.