The GraphHopper Directions API is tuned towards low bandwidth usage. E.g. we support http/2 and gzipped responses. Then e.g. the Routing API supports to compress the routing geometry in a special format to further reduce bandwidth (you can disable this via
points_encoded=false) or returns path details in a compact format.
Now we added support to gzip POST requests (not just the response) to reduce the bandwidth usage for the Matrix and Route Optimization API. The only change you need is to specify the header
Content-Encoding: gzip for those requests.
You can find the latest information about this topic in our documentation.