What is a GPX file?
A GPX file (GPS Exchange Format) is a text file with GPS points in it: coordinates, in order, sometimes with a name or a time. That's the whole thing. It's what a ride recording is saved as, and what a route is shared as.
It does not carry a map. No roads, no terrain, no satellite pictures. The map comes from the app you open the file with, which is why the same file can look different from one app to the next.
What an app draws from those points depends on what they describe. OffTrail shows a Track exactly as it was recorded, and joins the points of a route with straight lines. It doesn't pick roads for you in between.
What's inside: Track, route, waypoint
A GPX can hold three kinds of thing, and they behave differently.
Inside the file, a few lines like these are the points:
<trkpt lat="40.2826" lon="-7.5079"> <ele>812</ele> <time>2026-10-24T09:12:00Z</time></trkpt>
That's all it is: points.
Why does my GPX look different in another app?
Because the file stores points, not the path between them. A Track already has so many points that every app draws roughly the same line. A route has few, so what happens between them is up to the app: one calculates a road path from point to point, another draws straight segments. Same file, two different lines.
The map underneath is the app's too, so roads and trails you see around the line are never part of the file.
Where GPX files come from
You record one on a ride, export one from a planner such as the OffTrail Route Planner, download one from a trail-sharing site, or get one from a friend or an event organiser.
Open one on your phone
A GPX is not a picture, so tapping it needs an app that reads it. The steps depend on the phone: iPhone or Android.
Without signal
GPS doesn't need a connection: your phone works out where it is from satellites. The map is what needs to be on the phone, so download it for the whole area first. Can you use GPS without internet? has the checklist.
Before you leave, switch mobile data off and open the Track once. If the line and the map both show, you're set.
Frequently asked questions
What's the difference between a Track and a route?
A Track is a path that was recorded or drawn point by point, so it follows the exact line. A route is a short list of points; an app may calculate a path between them, or just join them with straight lines.
Does a GPX file include the map?
No. It only holds coordinates, and sometimes names and times. The map comes from the app you open it with, so download the map for the area before you go.
How do I open a GPX file on my phone?
Save the file, then open it with a navigation app that reads GPX. The steps differ by phone: see the iPhone and Android guides.
What's the difference between GPX and KML?
Both are text files with coordinates. GPX is the usual format for navigation and recorded rides; KML is mostly used for placing things on a map. OffTrail opens GPX files, not KML.
Following a GPX in OffTrail
Import the file and OffTrail draws it on an offline map, warns you when you leave the line, and records your ride. More on GPX navigation.