Repair a broken activity file

Most file problems that make an upload fail — a training platform rejecting a file, a map tool drawing a route that teleports across a city, a duration that comes out negative — trace back to one of a small number of underlying faults, and this tool is built to find and fix that specific set rather than attempt some vague general cleanup. It checks for a damaged or corrupted file header and recovers whatever activity data is still readable behind it, timestamps that are out of order and need reordering, timestamps missing entirely and needing to be filled in by interpolation from the points around them, duplicate points recorded at the same instant, and GPS spikes — a single point that jumps to an impossible position and back — along with sustained stretches where the implied speed simply isn't physically plausible. What matters as much as the fixes themselves is the order of operations: every finding is shown to you before anything is changed. You see exactly what was wrong, point by point or issue by issue, and only after that does the tool apply the fix — nothing is silently rewritten behind your back. That includes the opposite case too: if a file turns out to be sound, the tool reports it as already fine rather than inventing a change just to have done something. This distinction matters most when you're troubleshooting a real upload failure and need to know whether the problem was actually in the file or somewhere else in your workflow. The whole process — scanning, reporting, and fixing — runs locally inside your browser, so a file with a sensitive route never has to leave your device to get diagnosed. Free for files up to 25 MB, three at a time.