Browse every message and field inside a raw FIT file.

No - this tool is strictly read-only. It is the diagnostic counterpart to the rest of the suite. When you need to change a file, use the other utilities: [FIT Time Adjuster](/tools/fit-time-adjuster) for clock shifts, [FIT Sport Changer](/tools/fit-sport-changer) for sport rewriting, [FIT Device Changer](/tools/fit-device-changer) for device metadata, and so on.

The FIT format stores latitude and longitude as semicircles - a 32-bit signed integer where 2^31 semicircles equals 180 degrees. The raw values look like 535124800 instead of 47.85. We convert any field name ending in _lat or _long to decimal degrees so you see the human-readable coordinate next to the raw int.

No - the tables virtualise via the browser's native scrolling, so you can click into a record table with 30,000 entries and the UI stays snappy. The decode itself takes about a second per hour of activity on a modern laptop. Files from a long brevet or 24-hour ride open without trouble.

For an activity file: start with file_id (manufacturer, product, time created), session (the summary record - total distance, total time, averages), lap (per-lap summaries), record (per-second data), and event (start/stop, lap presses, autopause triggers). For a course file: course, course_point (turn prompts), and record. For a workout file: workout and workout_step.

Often yes. We use the official Garmin SDK with strict validation off, so files with minor corruption or non-standard extensions still display what they can. If even the Inspector cannot decode it, the file is genuinely broken and you need a recovery tool - or a fresh export from the source.

Open the device_info messages. The manufacturer field is the Garmin enum (or wahoo_fitness, suunto, coros, etc), and the product field is the device model. The first device_info row is usually the head unit or watch itself; later rows are paired sensors (HRM, power meter, cadence sensor, etc).

Garmin reserves space in the FIT spec for vendor-specific extensions, and Wahoo, Stages, Coros, and Polar all use it for proprietary data. The unknown message types are usually private vendor data that Strava and Garmin Connect ignore. They are harmless - they just are not in the public spec.

Developer fields are custom fields written into the FIT by a third-party app or Connect IQ data field. They have their own field_description messages declaring their name and units. The Inspector renders both the field_description tables and the developer-field columns inline with the standard fields.