Repair a broken activity file

A GPX, TCX, or KML file is XML — plain text wrapped in nested tags — and that text has to open with a clean declaration and root element before anything after it means anything to a parser. When a handful of bytes near the very start get mangled — a failed download, a bad copy-paste, an editor that saved with the wrong encoding, a sync tool that truncated the first line — most viewers refuse the whole file, even though every trackpoint after that point is untouched. That mismatch, a broken few bytes wrecking an otherwise-complete recording, is what this page is about. FitFileHub's repair tool scans past the damaged prefix looking for the real root element — the actual gpx, TrainingCenterDatabase, or kml tag your file is built around — and, if it finds one with intact track data behind it, discards only the corrupted lead-in and keeps everything from there on. It shows you what it found before changing anything: a file that's one of the many that look broken but parse cleanly gets reported as already fine rather than rewritten for no reason. Two honest limits are worth knowing. This recovery targets damage at the header specifically — it won't help if the corruption runs throughout the file, since there's no longer a clean point to recover from. And it doesn't apply to FIT files at all: FIT is binary with no XML declaration to repair, so a damaged FIT header fails in a different way (there's a dedicated page for that case). Everything runs locally in your browser — the file with your route never leaves your device to get diagnosed or fixed. Free for files up to 25 MB, three at a time, no account required.