The official GEOS code repository is the GIT repository (http://git.osgeo.org/gogs/geos/geos.git). Clone with: `git clone https://git.osgeo.org/gogs/geos/geos.git` Nightly snapshot can be found on http://geos.osgeo.org/snapshots/ A number of CodeMirrors do exist for users and contributor's convenience.