What This FIT File Analyzer Checks
The tool reads the FIT header, local message definitions, activity records, session summaries, device information, and CRC values. It then reports whether key streams such as timestamp, GPS, heart rate, cadence, power, speed, altitude, and distance are present.
When to Use a FIT File Viewer Online
Upload failure
Check whether a Garmin or Strava upload issue may be caused by a damaged or incomplete FIT file.
Missing data
Confirm whether heart rate, power, cadence, GPS, altitude, or distance are actually inside the file.
Spreadsheet analysis
Export record-level data to CSV for Excel, Google Sheets, R, or Python.
Device debugging
Inspect profile version, manufacturer fields, sessions, laps, and record counts.
FIT File Analyzer vs Repair Tool
This page focuses on analysis: what is in the file, whether the file passes CRC checks, which data streams are present, and what can be exported to CSV. If a file is corrupted, the warnings can help you decide whether you need a dedicated FIT repair tool, a device re-sync, or a manual merge from another activity source.
Privacy Notes for Activity Files
FIT activity files can contain GPS routes, timestamps, heart rate, power, cadence, device identifiers, and location patterns. This analyzer is built to run locally in the browser so users can inspect sensitive training data without uploading it to a server.
Not for Astronomy FITS Files
FIT and FITS are different formats. This tool is for sports and fitness `.fit` activity files. It is not designed for `.fits` astronomy image files.