Do you need to the files, or just look at them?
A popular freeware IFC viewer that also handles Revit files with the right plugins. It is highly optimized for large BIM models and offers advanced measurement tools. revit file viewer free download
Download the 30-day free trial of the latest Revit version. Do you need to the files, or just look at them
💡 If you only need to see the 3D geometry and don't care about the BIM data, ask the creator to export the file to a DWF format. DWF files are much smaller and can be opened by the free Autodesk Design Review software. Do you need to the files
If you don't want to install the massive Revit package, several lightweight alternatives offer great functionality for free.