Add download format GPX
Please provide a second download format: .GPX
Reason: Unlike GIS-software like QGIS or JOSM, other software or GPS
devices are not able to load Geojson files. An universal file format
which all of this other software and devices are able to read is GPX.
Would be great if we can choose between Geojson and GPX for download so
we don't have to use external file converters.
The GPX format isn't likely to be added. Mostly because it's not a format that PostgreSQL/PostGIS can output for us. There are libraries available that supports many formats, like for example GeoPHP, but with the data sizes handled here it's unlikely that we would be able to convert the data using PHP. It's likely to need an insane amount of RAM with a high-level language like PHP, which the site is written in.
KML is planned though, suggested in this ticket. PostGIS EWKT has been implemented in the back-end code today actually, but the front-end parameters aren't exposed yet. I doubt this will help you though.
With EWKT being implemented today it should be fairly easy to implement support for KML as well, but we haven't looked closer at it yet.