GIS Convert converts spatial data between formats entirely in the browser: Shapefile, GeoJSON, TopoJSON, KML/KMZ, GPX, GML, CSV, and WKT, with reprojection across 180+ coordinate systems. Nothing is uploaded — files are parsed and converted client-side, then downloaded back out.
It also validates geometry and previews the result on a map before you export, so you can catch a bad file before it breaks a downstream pipeline.
I built it for the same reason as MapLab: people kept handing me spatial files in the wrong format and I was tired of doing the conversion by hand.