Are you working with game files or scientific data files? Knowing the origin of your VTX file can help narrow down the best tool. FBX Review | Cross-platform 3D model viewer - Autodesk
For simple static meshes without complex rigging, some web-based tools like claim to handle various 3D formats, though they may struggle with the multi-file nature of Source Engine assets. Summary Table File Extension Role in Conversion .vtx Part of the source data; contains vertex info. .mdl The "brain" of the model; point Crowbar here. .smd The intermediate format used after decompiling. .fbx The final industry-standard format for Unity/Unreal. FBX Converter Online (Free) - Convert 3D models vtx to fbx