I\'m working on a web application that manages VRML files. I also want to let users see the uploaded files, without requiring a specific plug-in or player. X3DOM allows viewing
ok so i think this is the full solution for you
1) user uploads a vrml file
2) that file gets saved to (file or db)
3) upon confirmation that the vrml file has been saved (and possibly validated as correct vrml syntax) it gets converted and saved to x3d (again as file or db) , with aopt this would be accomplished by aopt -i input.wrl -o output.x3d
FYI: aopt is avail for linux windows and mac
since you use python this maybe a way you could do it as well with blender although there are no full example of vrml to x3d this link should get you started http://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Import-Export/Wavefront_OBJ#Command_Line_Converting
4) display the x3d via x3dom