The free FIT file toolkit. 14 tools. Zero uploads.

FIT file questions, answered.

Everything we get asked about the FIT format, FIT editing, and the toolkit itself.

What is a FIT file?

FIT (Flexible and Interoperable Data Transfer) is the binary format Garmin invented for activity and course files. Almost every modern bike computer, GPS watch, and trainer writes FIT - it carries records (per-second GPS, HR, power, cadence, temperature), laps, sessions, course points, workout steps, and rich device metadata that simpler formats like GPX can't hold.

How do I open a FIT file?

Drop it into the FIT Viewer above. It decodes in your browser using the official Garmin SDK and renders the route on a map plus elevation, power, HR, cadence, and speed charts. No software install, no upload.

Can I edit a FIT file online?

Yes - and this is exactly what most of these tools do. Change the sport, shift timestamps, remove a section, strip privacy zones around home, repair spikes in HR or power, set or refetch elevation, change the recorded device, and more. Every editor re-encodes with the official Garmin SDK so the output stays valid and Strava/Garmin Connect will accept it.

Are FIT file tools safe to use?

These ones are. Every tool runs entirely in your browser - your file never gets uploaded, never gets stored on a server, never lands in a logging pipeline. The only way the file leaves your device is if you click download. Be cautious about FIT editors that ask you to upload your file to their server; you have no way to verify what they do with it.

Do these tools work with Garmin, Wahoo, Coros, and Polar?

Yes. The FIT format is the same across manufacturers - it's the standard binary every major sports device writes. Garmin Edge / Fenix / Forerunner, Wahoo ELEMNT BOLT/ROAM, Coros Pace/Apex/Vertix, Polar Vantage/Grit/Ignite - if it writes a .fit file, these tools read and write it.

What's the difference between FIT, GPX, and TCX?

FIT is the binary format Garmin made for activity files - rich metadata, small files, but binary so you can't open it in a text editor. GPX is the universal XML format for routes and tracks; it carries trackpoints and elevation but lacks first-class slots for power, lap structure, and device metadata. TCX is Garmin's older XML format - heavier than GPX but with lap and HR/cadence/power slots. Use FIT for full fidelity, GPX to share with anyone, TCX for legacy training platforms.

Can I convert a FIT to GPX?

Yes - drop the FIT in the FIT ↔ GPX ↔ TCX Converter and pick GPX. The route, elevation, and timestamps carry over. Power gets written into the Garmin TrackPoint extension. If you need every field preserved exactly (laps, sessions, device info), keep the FIT or convert to TCX instead.

Are these tools free?

Every tool here is free, with no signup, no watermark, no usage limit, no upsell mid-flow. The reason they exist is that the big platforms either charge for these jobs or just don't do them. If you want to save your training to a real log that belongs to you, sign up for NeverChill - but the tools are free either way.