The Autodesk Viewer is available from here if you want to test it out while following along with the below guide. To put this to the test, I have been able to run models in the Viewer Web Application on an old Chromebook (Celeron Processor, 2GB RAM), a mediocre phone from 3 years ago and even an old Galaxy Tab.

It is very accessible, easy to use and has no hardware requirements beyond the capacity for your device to be able to open a modern web browser and connect to the Internet.

The best free Revit Model tool at the moment is the Autodesk Viewer Web Application. As you can imagine, there are a huge number of potential options for viewing and reviewing Revit files However with the climate the way it is, with users not necessarily having modern hardware to hand, I have only been recommending one tool for reviewing Revit Files that is free. The need to work from home in recent months has led to a huge spike in questions directed towards me, specifically what software I use for reviewing Revit Models when I do not have access to my main tower.

Free revit viewer