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 include official specifications and platform help, and guides show when their copy was last reviewed.
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 — when available, real files, accounts and devices. We distinguish this from a review of documentation.
We do not cite competitor blogs or forum posts as sources.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 reviewed
Our "open a GPX file in…" guides describe steps for apps and devices. We review the copy against official platform help where available before publication, link to the sources on each guide, and show its last review date. A hands-on verification date appears only when we have observed the published steps end to end with the needed account or device; it is separate from the publication decision. Platforms change their menus, so if a guide drifts, we treat it as a bug. Email contact@gpxviewer.app and we'll correct it.
Use of AI
We use AI tools to help draft and review content and code, the way many small teams now do. Platform-guide copy is reviewed against official help where available, and claims about our app are checked against its behaviour before they ship. Hands-on checks of other platforms are identified separately. 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.