Neverchill

Free toolkit · FIT Toolkit

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

14 free tools to view, edit, fix and convert your Garmin FIT files.

Open the FIT viewer

Free · no signup · your file stays on your device

14 free tools, one suite
Zero uploads. Files stay on your device.

Everything you need to work with Garmin FIT files, all in one place and all free. View FIT files in your browser, convert FIT to GPX, TCX, JSON, or CSV, merge FIT files back-to-back, remove a section from a FIT file, edit a Garmin FIT file's sport, device, or timestamps, repair a broken FIT recording, strip your home address before sharing, and a dozen other jobs the big platforms either charge for or simply don't do. Every tool decodes the binary FIT format with the official Garmin SDK inside your browser - your activity file never leaves your device, never gets uploaded to a server, and never lands in an analytics queue. Drop a file, pick a tool, download the result. Built for cyclists and runners who got burned by paid FIT file editors, shady online converters, or platforms that hold your data hostage. Works with FIT files from Garmin Edge, Fenix, Forerunner, Wahoo ELEMNT, Coros Apex/Pace/Vertix, Polar Vantage/Grit/Ignite, and any other device that writes the standard FIT format. Compatible with FIT activity files, FIT course files, and FIT workout files where the tool's job applies. Pair it with the GPX and TCX support across the suite and you have the most complete free FIT file viewer, editor, repair tool, and converter on the web - period.

14 free tools

Every job you need to do with a FIT file.

View, convert, merge, trim, repair, anonymise, edit metadata. Drop a file, pick a tool, get the result. No upload, no signup, no watermark.

GPX preview
0
km
Distance

GPX & FIT File Viewer

Open .fit, .gpx, .tcx files in one click.

Open
file
.fit
file
.gpx
file
.tcx
One-click conversion

FIT ↔ GPX ↔ TCX Converter

Any format in. Any format out.

Open
0
→ 1
Files merged
Stitching segments

FIT Combiner

Merge 2+ files into one activity, in your order.

Open
Section cut
Stitched clean

FIT Section Remover

Snip out the part of the ride you don't want.

Open
Breaks detected
-22:14 idle

FIT Break Remover

Cut the coffee stop, keep the ride.

Open
Outlier 1842 W
Capped at 420 W

FIT Peak Remover

Kill the bogus spikes, keep everything else.

Open
Tue 14 May
Sat 18 May

FIT Time Adjuster

Fix the clock without re-doing the workout.

Open
Today · 07:00
Tomorrow · 07:00
Clone

Clone & Retime

Re-stage any ride for any clock.

Open
Cycling Running

FIT Sport Changer

Tell every platform what you actually did.

Open
GARMIN
WAHOO
SUUNTO
COROS

FIT Device Changer

Tell the file which device it came from.

Open
0
m
Elevation set
Re-baselined

FIT Elevation Setter

Fix flat trainer rides or noisy phone tracks.

Open
Original start
Pre-roll added

FIT Start Extender

Backdate the start to a real coordinate.

Open
HR
Power
Streams merged

FIT Field Merger

Patch missing streams from a parallel recording.

Open
activity.fitdecoded
0F A3 21 B7 4Ctimestamp: 2026-06-02T10:32:14Z
12 8A 64 02 1Fposition_lat: 51.5074
04 71 9E 33 88position_lng: -0.1278
0A 22 4D 6E 91altitude: 142.6 m
7E 55 03 9C 41heart_rate: 152 bpm
88 1D B4 E2 0Fpower: 248 W
3C C9 76 18 5Bcadence: 92 rpm
20 81 4A E6 7Dtemperature: 18 C
Bytes decoded

FIT Inspector

Read-only deep dive on what's actually in your FIT.

Open

How it works

Same three steps for every tool in the suite.

1

Drop your file

FIT, GPX, or TCX from any watch, head unit, or training platform. It decodes in your browser - nothing uploads.

2

Pick a tool

Convert, merge, trim, fix elevation, strip privacy, repair spikes - whatever the job is. 14 tools, one suite.

3

Download the result

Same format in, same format out (or any other you choose). Re-upload to Strava, Garmin Connect, Komoot, anywhere.

Why this toolkit

Built by athletes who got tired of paid FIT editors and shady online converters.

  • Powered by the official Garmin FIT SDK
  • Works fully in your browser - your file stays on your device
  • Round-trip safe encoding preserves every field
  • Free forever, no signup, no watermarks

More free tools

Pair the FIT toolkit with the calculators.

Pace Calculator

Pace, time, distance - three ways.

Open

FTP Estimator

20-min test or ramp test, then zones.

Open

Power-to-Weight

Watts per kilogram for every duration.

Open

TSS Calculator

TSS, IF, and intensity band per ride.

Open

Race Time Predictor

Riegel projections across distances.

Open

HR Zone Calculator

Karvonen or LTHR zones.

Open

VO2 Max Estimator

Race, Cooper, or Rockport tests.

Open

Marathon Pace Charts

Even-split tables for any goal time.

Open

Neverchill FIT Toolkit

29 free tools. Zero uploads.

Every tool decodes your activity file in your browser using the official Garmin SDK. Your file never leaves your device.

FIT File Viewer

Open .fit, .gpx, .tcx files in one click.

FIT Converter

Convert FIT to GPX, TCX, JSON, or CSV.

FIT Combiner

Stitch multiple rides into one seamless activity.

Explore the FIT toolkit Browse all 29 tools

FIT file questions, answered.

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

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.