100% private — files never leave your browser
FIT Viewer
See what is inside a .fit file without installing anything or logging in anywhere. The track renders on a map next to distance, duration, ascent, heart rate and laps — decoded from the binary on your device, never uploaded. No Garmin account required.
or click to browse — FIT, GPX and TCX all accepted, format detected automatically
How to view a FIT file
- 1
Drop the file
Drag the .fit file onto the box above or click to browse. No account, no plugin, no upload dialog — the file opens straight off your disk.
- 2
Decoding happens locally
The binary is decoded in a background worker on your device. Large files with dense record streams open without freezing the page.
- 3
Read the map
The track draws on the map with laps as distinct segments. Zoom into the interesting parts — the climb, the descent, the sprint — and the map keeps up.
- 4
Read the stats
Distance, duration, ascent, heart rate and the lap list sit beside the map. Check them against what the device claimed before you share or upload the file.
Why view FIT files in a browser?
FIT is the format every Garmin, Wahoo, COROS and Zwift device writes — and almost no desktop software opens. The usual route is uploading to Garmin Connect, which wants an account and a copy of your file. When a friend shares a ride, a coach wants a quick look at an athlete's file, or you exported one from a platform, a browser viewer is the fastest way in.
It is also the natural second opinion on tool output. Converted a FIT to GPX, merged two rides, split a monster file? Open the result here and check that distance, ascent and the shape of the track match what you expected — before you upload it anywhere or delete the original.
How the viewer works
FIT is a compact binary format, so there is nothing to eyeball in a text editor. The viewer decodes the file's messages — file_id, session, laps and the record stream — in a Web Worker on your device, then draws the records on an OpenStreetMap-based map. Laps render as distinct segments, so interval structure is visible at a glance.
The statistics come from the decoded file: distance, duration and ascent from the session, average and maximum heart rate when recorded, the lap list, and the sport and device named in the file's headers. Where a summary is missing, the numbers are computed from the points rather than guessed — and a truncated or corrupt file fails loudly with a clear error, never invented numbers.
When a desktop tool is the better answer
This is a viewer, not an analysis package. Questions like how your power zones trend across a training block, or how eight weeks compare, belong in GoldenCheetah, TrainingPeaks or similar. The viewer answers what a file contains; training intelligence needs a training tool.
FIT is also a poor format for editing — if a track needs surgery, converting to GPX first is the practical path, since readable XML beats binary surgery. A file that will not decode at all is a repair problem: Repair FIT File rebuilds a damaged header, CRC or truncated stream in the browser, still without uploading.
Your files never leave this browser
This tool — like every tool on this site — runs entirely as client-side JavaScript. The file you drop is parsed in a Web Worker on your own device, converted in memory and handed straight back to you as a download. There is no upload endpoint, no server-side conversion service and no temporary storage: you can watch the network tab in your browser's developer tools and confirm that no file bytes are transmitted anywhere.
That matters more with fitness data than with most files. A GPS track is a precise log of where you were, at what time, and how hard your heart was working — home address, training habits, favorite routes and race schedule all in one file. Keeping conversion on-device means third-party converters never get a copy of that log, and the tool keeps working identically on a plane, in a basement, or anywhere else without signal.
Frequently asked questions
No. The viewer runs entirely in your browser and decodes the file locally — Garmin's servers are never involved. It also makes a quick inspection tool when you are away from your own devices and accounts.