Merge split Garmin FIT files into one activity — on Mac or in your browser

Pressed stop by accident, or the watch battery died mid-activity? We are planning a small tool that joins the pieces back into a single FIT file.

What it is planned to do

• Merge 2 or more FIT files from one activity into one file.
• Aim: a result that Garmin Connect accepts on import, with correct total elapsed time and averages.
• Works on a Mac and in a web browser. No Windows needed.
• Intended to run locally in your browser, so your files stay with you. (Planned; not final.)

Honest limitations

• Not built yet — this page tests whether people want it.
• We cannot promise acceptance by every device, platform or app; FIT files from different devices can behave differently.
• Meant for pieces of the same activity, not for combining different workouts.
• Not affiliated with Garmin.