Shift an activity's timestamps

A device set to the wrong timezone, or one that wasn't started the moment you actually began moving, produces a file where every timestamp is off by the same fixed amount — not corrupted, not out of order, just uniformly shifted from what actually happened. Time-shift is built for exactly that single problem: apply one offset, positive or negative, down to the second if needed, and every timestamp in the file moves by that same amount. The interval between consecutive points doesn't change at all — if two points were four seconds apart before the shift, they're four seconds apart after it, since it's the absolute time that was wrong, not the pacing or duration of the recording. That distinction is why this is a narrower, more predictable tool than repair: repair looks for timestamps that are internally inconsistent with each other and tries to fix that inconsistency, while time-shift assumes the recording is internally consistent already and just needs to be moved to the correct point on the clock, which is the common case when the root cause is a timezone setting rather than a device malfunction. This matters more than it might seem for anything that gets compared across files or synced to a training calendar — a ride logged three hours off from when it actually happened can throw off day-of-week training summaries, overlap incorrectly with a different activity, or simply look wrong sitting next to correctly timed files from the same week. The shift is applied entirely inside your browser once you enter the offset; the file isn't uploaded to compute it. Works across FIT, GPX, TCX, and the other formats this site reads. Free for files up to 25 MB, three at a time.