Why your file never leaves your browser
Every online converter uploads your file to a server. This one does not, and you do not have to take our word for it: you can check in thirty seconds.
Why it matters
A GPS track is not a neutral document. It records where you have been, at what time, and it usually starts at your own front door. It shows your Sunday routes, the roads you take to work, the place you stopped for lunch. Handing that to a stranger to have a file extension changed is a bad trade, and nobody would make it if the trade were stated out loud.
How it works
Your browser already knows how to read a file from your disk and how to hand a file back. The missing piece was the conversion itself, and that is written in JavaScript and runs on the page you are looking at. Reading uses the browser's own FileReader; the result is assembled in memory as a Blob and saved by the browser directly. Between those two steps there is no server, so there is nothing to upload, nothing to store and nothing to delete afterwards.
Verify it yourself
- Open one of the tools - the GPX to KML one, for instance.
- Open your browser's developer tools (F12, or Ctrl+Shift+I, or Cmd+Option+I on a Mac) and go to the Network tab.
- Convert a file.
- Look at the list. Map tiles appear, because the preview map draws them. Your file does not appear, because it was never sent.
The browser enforces it, not just us
Saying "we do not upload your file" is a promise. The interesting part is that the page cannot upload it even by mistake. The site sends a Content-Security-Policy header with connect-src 'self', which tells your browser to block any network request from this page to anywhere but this site. If a bug, or a careless change, or a compromised third-party script ever tried to send your track somewhere, the browser would refuse. It is the difference between a policy and a lock.
The one exception, said plainly
One tool out of five does talk to our server: Google Maps to GPX. It has to, and the reason is the browser's rules rather than our choice - following a short maps.app.goo.gl link, looking up place names, and asking a routing engine for the roads are all requests a web page is not allowed to make to another site. What gets sent is the link you paste, never a file, and nothing is kept once the answer is on its way. A Google Maps link can reveal where you are going, so if that matters to you, that is the tool to think twice about.
Why almost nobody else does this
Not because it is secret, but because it is more work. Uploading a file and running an existing library on a server is the shortest path from nothing to a working converter; writing the parsing and the writing of GPX, KML and KMZ in JavaScript is a few hundred lines that have to be right. The shortcut is invisible to whoever uses the site - which is exactly why it is worth saying which of the two you are looking at.
The tools
You have the GPX and you want the route on your phone. Get a ready-made Google Maps link, plus a KML that keeps every single point for Google My Maps.
in your browserGoogle MapsGPXYou planned the route on Google Maps and your sat-nav wants a GPX. The roads between your stops are rebuilt point by point, and you can correct them on the map.
needs our serverGPXKMLYou want the track in Google My Maps or Google Earth, with every point kept - not the eleven stops a Maps link can hold.
in your browserKMLGPXYou drew the route in Google My Maps or Google Earth. This is the most faithful conversion there is: a KML already contains the line you drew, so nothing has to be guessed.
in your browserGPX / KML / KMZYou just want to see what is in the file: the track on a map, its distance, its points, and the time it took.
in your browser