Because Fitbit is not mentioned anywhere as a supported device, I thought I should report that it actually works very well for me. I am using a combination of iPhone and Fitbit Charge 2. GPS/Track recording happens via iPhone and HR recording via Fitbit Charge 2. Sessions can be downloaded manually (but quickly and without problems) as TCX filed using the Fitbit.com interface. I exported 6months of training yesterday and now I’m looking at a lot of very helpful calculations and predictions on runalyze.com
Thanks for providing such an outstanding tool!!!