Methodology
How GPX Viewer decides what to show, where its information comes from, and how its guides are kept accurate. The short version: numbers come only from your file, sources are official specifications, and guides are verified against the real thing.
Where our information comes from
We work from a strict source hierarchy, in this order:
- Official specifications — the TopoGrafix GPX 1.1 XSD, the OGC KML specification, IETF RFC 7946 (GeoJSON), the W3C File API, and Garmin's published XSDs (TrackPointExtension, FIT).
- Vendor documentation — the official help pages of the platforms and devices we describe.
- Hands-on testing — real files, real accounts and real devices, done by us.
We do not cite competitor blogs or forum posts as sources. If a claim can't be traced to a specification, vendor documentation, or our own testing, we don't make it.
How the metrics are computed
Every figure GPX Viewer shows is derived only from the contents of your file — nothing is estimated, modelled, or filled in. Distance is the cumulative great-circle (haversine) distance between consecutive points; elevation gain and loss use a 2-metre hysteresis filter to reject GPS/barometric noise; speed is each point's distance divided by the time to the next; average speed is the mean of the moving per-point speeds. The full definitions are on the homepage under "How the metrics are computed", and they are kept in step with the code that actually runs. If your file lacks timestamps, we show distance and elevation and clearly say that speed and duration can't be derived — we never invent them.
How the platform guides are verified
Our "open a GPX file in…" guides describe exact steps for apps and devices. Each guide
is checked against the live platform — with a real account where one is needed — before it is published, and
each carries a verified date. Platforms change their menus; when a guide drifts, we treat it as a
bug. Email contact@gpxviewer.app and we'll fix it. A wrong guide is
worse than no guide, so we would rather remove a step we can't stand behind than leave it up.
Use of AI
We use AI tools to help draft and review content and code, the way many small teams now do. Everything is checked against the primary sources above and against the app's actual behaviour before it ships — the responsibility for accuracy is ours, not a model's. We mention this because honesty about how the work is made is part of being trustworthy.
The sample files
Our sample GPX corpus is built by a deterministic generator. The land routes follow real roads and paths (generated from OpenStreetMap data with the BRouter engine, so they look like genuine tracks) and carry OpenStreetMap attribution under the ODbL; the water tracks and the waypoints file are synthetic and released as CC0. No sample is a personal recording — every timestamp is synthetic. The generator is byte- deterministic, so the files never change unless we change them on purpose.