This tool is being developed by the WoW community for the WoW community and as such won't have watermarks all over it but will likely also be more unstable/bleeding edge. Currently it supports rendering most M2 models (smaller more complex models, characters unsupported for now), WMO models (larger models) and ADT files (terrain files with WMOs and M2s).
These parts of it are open source (more coming in the future!):
This requires a browser that supports both WebAssembly (see list here) and WebGL 2.0 (see list here). If your browser does not support this the modelviewer will definitely get upset and will definitely throw errors towards your general direction. We're aware this is not always supported on some configurations, but are hopeful it will be in the future!
For ADTs and WMOs, the model viewer uses a free-roam camera. It can be controlled via dragging the mouse and WASD keys. Holding SHIFT increases camera speed.
For M2s, the model viewer uses a rotational camera. You can rotate the model by dragging the mouse and zoom out with the scroll wheel. If skins/animations are available, a menu will pop up with options for these.
This modelviewer (and especially the UI) is still a heavy work in progress. Many bugs will appear. Report any issues/feature requests via GitHub by clicking the "Report issues" button or via Discord by joining through the link in the menu.
An embeddable version of the modelviewer is being worked on, but the full fledged version still has priority. Decisions on how exactly it will work (or how costs will be dealt with if it gets popular) are still to be decided.