Free local file tool

FIT File Viewer Online

Open a Garmin FIT file and inspect its details, activity summary, integrity status, and decoded messages. Everything runs on this device—nothing is uploaded, and reading the file uses no network connection.

Runs locally. No upload. No network.

The FIT file is read and decoded entirely on this device. Its location, health data, messages, and device identifiers never leave your device.

Messages only—no maps or charts

This version focuses on file details, integrity checks, and raw FIT messages. It does not draw routes on a map or generate charts.

Choose a FIT file
Choose .FIT fileor drag it here
One .fit file, up to 25 MB. Nothing is uploaded.

Drop a .fit file to begin

The viewer can read FIT activities, workouts, courses, wellness data, device data, and other standard FIT message types.

What does a FIT File Viewer show?

A FIT File Viewer decodes the binary Flexible and Interoperable Data Transfer format used by Garmin and other fitness devices. This viewer exposes the file header, identity, summary, integrity checks, and the complete set of decoded message groups.

Identify the file

See whether the FIT file contains an activity, workout, course, settings, wellness data, or another FIT data type, plus its device and creation metadata.

Check integrity

Validate the .FIT signature, expected file size, header CRC when present, and file CRC using Garmin's official JavaScript SDK.

Inspect every message type

Browse records, sessions, laps, events, workouts, courses, developer fields, and every other decoded message group.

How to open a FIT file

1

Choose the .fit file

Select one FIT file from your computer or drag it into the viewer. Files are limited to 25 MB.

2

Inspect the results

Review file identity, activity-level values, CRC status, decoder warnings, and each available FIT message type.

3

Export what you need

Download all decoded data as JSON or one message group as CSV. The export is created locally without a network connection.

FIT File Viewer FAQ

What is a FIT file?
FIT stands for Flexible and Interoperable Data Transfer. It is a compact binary format used by Garmin and many fitness devices for activities, workouts, courses, health data, settings, and other sports data.
Is my FIT file uploaded?
No. The file is read entirely on your device. It is not uploaded, and Trainingload.ai never receives the file bytes or decoded contents.
Which FIT files can this viewer open?
It can inspect standard FIT files recognized by the official Garmin FIT JavaScript SDK, including activity, workout, course, wellness, and device-related files up to 25 MB.
What does a failed CRC check mean?
It means the file signature, declared size, header CRC, or file CRC did not pass Garmin SDK integrity checks. The file may be incomplete, corrupted, or exported in a non-standard way; partial messages may still be readable.
Can I view FIT developer fields?
Yes. The decoder includes recognized developer-defined fields and reports how many developer field descriptions were encountered.

Based on the official FIT SDK

File decoding and CRC validation use Garmin's official FIT JavaScript SDK. You can review its source code on GitHub or read Garmin's FIT developer documentation.

Garmin FIT JavaScript SDK on GitHubGarmin FIT SDK documentation
Last updated: July 18, 2026

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FIT File Viewer Online | Open FIT Files, No Upload