Reverse a GPX track

Flip a route so it runs the other way, for riding a loop anticlockwise or walking a trail back from the far end. The track is turned round in your browser and saved straight back to your device.

Your file is read on this device and never uploaded.

Then make it a film: Animate this route opens the track in Voyarc, which draws it on a real map and exports it as a video.

What it does, and what it does not

Writes the points in the opposite order, each with its own height, so the profile is the same hill climbed from the other side.
Mirrors the times rather than reversing them: the new track starts when the old one did, finishes when it did, and every gap between fixes is kept.
Reads KML, KMZ, TCX and GeoJSON too, and writes the reversed track as GPX.
Waypoints are not carried, and several segments become one line.

Questions

Why are the times not just reversed?

A reversed list of times would run backwards, and no app accepts a track whose clock goes back. Mirroring keeps the clock running forward with the same pace between each pair of points.

Will turn-by-turn directions follow the new direction?

A device that navigates along a track will follow the points in their new order. Turn cues written for the old direction are not part of a track and are not carried.

Does the distance change?

No. The same line the other way is the same length, and the climbing and the descent trade places.