basinkit
Click a river anywhere on Earth and get an analysis-ready basin package: elevation, land cover, soil, rainfall, surface water, rivers, and full Horton-Strahler morphometry, clipped to the basin.
Click a point on any river in the world and get the basin draining into it, then pull DEM, land cover, soil, rainfall, surface water, rivers and lakes for that basin -- clipped and masked to the polygon, not to its bounding box. No account is needed for any of it. Delineation is validated against published gauge areas on six continents, with a median area error below one percent.
Other plugins delineate from a clicked point, and Sen Hydro does it well through the same public mghydro service this plugin can use. Three things here are different. The data: elevation, land cover, soil, rainfall, surface water, rivers and lakes come back as layers clipped to the polygon, not as a report. The morphometry: the full Horton-Strahler-Schumm set from one algorithm, with Strahler streams counted as streams rather than as the reaches a river dataset splits them into. And the offline path: the default backend walks the HydroBASINS level-12 graph from a cached local copy, so after the first download it needs no network at all. Every algorithm is a Processing algorithm, so batch mode, the Model Builder and qgis_process all work.
EXTERNAL DEPENDENCY: this plugin requires the Python package "basinkit", which QGIS does not ship. If it is missing the plugin will tell you the exact pip command for your QGIS Python installation. See the plugin homepage for details.