postrunner

https://github.com/scrapper/postrunner

PostRunner is an application to manage FIT files such as those produced by Garmin products like the Forerunner 620 (FR620), Forerunner 25 (FR25), Fenix 3, Fenix 3HR, Fenix 5 (S and X). It allows you to import the files from the device and analyze the data. In addition to the common features like plotting pace, heart rates, elevation and other captured values it also provides a heart rate variability (HRV) and sleep analysis. It can also update satellite orbit prediction (EPO) data on the device to speed-up GPS fix times. It is an offline alternative to Garmin Connect. The software has been developed and tested on Linux but should work on other operating systems as well.