What it is
FitMerge takes the FIT, GPX or TCX files of one activity that got cut into pieces and hands back a single file, ready to upload. You drop the pieces onto the page, check the list it shows, and download the result as FIT, GPX or TCX. The reading and the joining both run inside your browser tab.
Why it exists
On Sunday 1 November 2026 I rode the MS Gong Ride, 80 km from Sydney to Wollongong. Somewhere along the way I pressed the wrong button on my bike computer, and the ride was saved as two activities instead of one.
Strava can't merge activities, and the tools I found either wanted my files uploaded to a server or wanted me to sign up first. So I wrote my own. I started building on Wednesday 4 November, and by Friday 6 November the site was live.
Who made it
Frank Z, a cyclist in Sydney. FitMerge is a side project of one person, not a company.
Principles
- Your activity files never leave your device. The page does the work locally and the download goes straight to you.
- It costs nothing and asks for no account. There are no ads either.
- It's independent. No watch maker, bike computer brand or training platform is behind it, and none has vouched for it.
What's next
Trips that span several days can now be merged. When the files fall on different days, the page asks you to confirm they are days of one trip; each night between them becomes a pause, with up to 48 hours from one day to the next. Anything else I add will go on this page once it works, not before.
Contact
A file that wouldn't merge, or something you'd like it to do? Write to me here.