[brownbat]

It's coming from Google Fit on Android Wear. I assume using accelerometer and possibly heartrate data, so should be available on most devices.

Fair warning though... It's brilliant in some ways and alpha in others. I can't seem to edit a set if I tap too fast and log it incorrectly. It guesses one rep too many in about 30% of sets.

On the other hand it knows when I'm doing pull ups (ie, without moving my wrist) and accurately counts them, which seems like magic.

It calculates an extrapolated one rep max for all your sets.

On the other hand the web interface is not exactly feature rich for data junkies. And I'm not sure there's an easy way to export your data to a more useful spreadsheet.

It's ripe for someone to make a great lifting app. But you know, watches are niche, so don't expect any customers.