FIT File Editor
Drop your .fit file here
or click to browse
I'm Jason, a software engineer and runner based in New York City. I built this tool to support my own training and I hope it helps yours too! If you have feedback or ideas, feel free to message me on Instagram or LinkedIn.
What is FIT File Editing?
Sometimes your FIT file data needs adjustments before uploading to Strava, Garmin Connect, or other platforms. Sensors can malfunction, activities can start recording too early or stop too late, and GPS data can drift. This free online FIT file editor lets you fix these issues directly in your browser.
The FIT (Flexible and Interoperable Data Transfer) format is a binary file standard developed by Garmin used by virtually every GPS fitness device. Editing these binary files normally requires specialized software, but this tool handles the decode-edit-encode process entirely in your browser using the official Garmin FIT SDK.
Common Use Cases for Editing FIT Files
- Trim warm-up and cool-down: Cut the beginning or end of a race file so only the race itself is included in your results.
- Remove heart rate spikes: Cap or zero out erroneous heart rate readings caused by sensor dropouts or interference.
- Correct power data: Scale power values when switching between power meters with different calibrations.
- Cut auto-pause gaps: Remove sections where your device failed to auto-pause, such as long traffic stops.
- Remove GPS drift: Cut the first few minutes of an activity where GPS accuracy was still settling.
- Fix cadence data: Set cadence to zero for walking sections that were incorrectly recorded as running.
How to Cut Sections from a FIT File
Cutting removes records from any part of your activity — the start, middle, or end. Use the interactive chart to visually select exactly what to remove.
- Upload your .fit file using drag-and-drop or the file browser
- Select the Cut tab
- Drag on the chart to highlight the section you want to remove, or enter record numbers manually
- Add multiple cuts if needed — cut ranges are shown in red on the chart
- Click Download Edited FIT to save your edited file
How to Edit Heart Rate Data in a FIT File
Heart rate sensor dropouts and spikes are common, especially with optical wrist sensors. Here's how to fix them:
- Upload your .fit file
- Select the Modify Fields tab
- Choose Heart Rate from the field dropdown
- Select an operation: Cap at maximum is useful for removing spikes (e.g., cap at 200 bpm), while Set to zero removes heart rate data entirely for a range
- Drag on the chart to select only the affected section, or apply to all records
- Click Apply Modification, then Download Edited FIT
Privacy & Security
This FIT file editor runs entirely in your browser. Your file is never uploaded to any server. All decoding, editing, and re-encoding happens locally on your device using JavaScript and the official Garmin FIT SDK, ensuring your fitness data stays completely private.
Supported Devices
This editor works with FIT files from any device or platform that produces .fit files, including:
- Garmin — Forerunner, Fenix, Edge, Venu, Enduro, Epix
- Wahoo — ELEMNT, KICKR
- COROS — PACE, VERTIX, APEX
- Suunto — All models with FIT export
- Zwift & TrainerRoad — Indoor ride and run files
- Strava — Original file exports from any activity
Common Questions (FAQ)
How do I edit a FIT file?
Upload your .fit file to this free online editor using drag-and-drop or the file browser. You can trim the start or end, cut out sections in the middle, and modify data fields like heart rate, power, cadence, speed, or altitude. All editing happens in your browser — your file is never uploaded to a server. Download the edited file when you're done and re-upload it to Strava, Garmin Connect, or any other platform.
Can you trim or crop a FIT file?
Yes. Use the Cut tab to trim the beginning or end of your activity, or remove any section in the middle. Drag on the interactive chart to visually select the range you want to cut, or enter record numbers manually. You can add multiple cuts before downloading. This is useful for removing warm-up, cool-down, or sections where your device failed to auto-pause.
How do I fix heart rate spikes in a FIT file?
Go to the Modify Fields tab, select Heart Rate, and use the Cap operation to set a maximum value (e.g., 200 bpm). This replaces any readings above your cap with the cap value. You can also use Set to zero to remove heart rate data entirely for a selected range, or drag on the chart to target only the affected section.
What FIT file editors are free?
This FIT file editor is 100% free with no signup required. It runs entirely in your browser using the official Garmin FIT SDK, so your data stays private. This editor supports trimming, cutting, and field modification (heart rate, power, cadence, speed, altitude) with an interactive chart for precise selections.
Can I edit power or cadence data in a FIT file?
Yes. Use the Modify Fields tab to select Power or Cadence. You can Set a fixed value across a range, Scale values by a multiplier (useful when switching between power meters), Cap at a maximum to remove spikes, or Zero out data for a selected range. Drag on the chart to apply changes to specific sections only.
Is it safe to edit FIT files online?
This editor processes everything locally in your browser. Your FIT file is never uploaded to any server. The tool uses the official Garmin FIT JavaScript SDK to decode, modify, and re-encode files entirely on your device, so your fitness data remains completely private. Want to explore your data before editing? Try the FIT File Viewer.