I did a quick review of the resources that you linked to:
https://portal.opentopography.org/raster?opentopoID=OTSRTM.0...
allows to submit a request for data from a specific area through a web form (no REST API), then you get redirected to a page where you get a download link after your request has been processed. Does not give access to the original SRTM data.
http://www.geonames.org/export/web-services.html
exposes SRTM data through a REST API in their own custom format. I immediately ran into rate limiting when I tried to download a small map tile.
https://download.geoservice.dlr.de/SRTM_XSAR/
provides free access to SRTM data in the original format. This is a great resource! Unfortunately, the map tiles cover 10x10 degrees, which results in huge files. NASA used to provide 1x1 degree tiles, which was much better suited for on-demand access.
https://portal.opentopography.org/raster?opentopoID=OTSRTM.0... allows to submit a request for data from a specific area through a web form (no REST API), then you get redirected to a page where you get a download link after your request has been processed. Does not give access to the original SRTM data.
http://www.geonames.org/export/web-services.html exposes SRTM data through a REST API in their own custom format. I immediately ran into rate limiting when I tried to download a small map tile.
https://download.geoservice.dlr.de/SRTM_XSAR/ provides free access to SRTM data in the original format. This is a great resource! Unfortunately, the map tiles cover 10x10 degrees, which results in huge files. NASA used to provide 1x1 degree tiles, which was much better suited for on-demand access.
https://download.geoservice.dlr.de/TDM30_EDEM/ DLR does provide 1x1 degree tiles for similar data sets like TanDEM-X, but for those they do not provide anonymous access.