While not free, Revit LT is a stripped-down, more affordable version. Autodesk also offers a trial for LT.
If you are a student or educator, Autodesk provides free 1-year access to all Revit versions, including 2021. Renew annually at no cost. You need a valid school email and proof of enrollment/employment.
Autodesk offers a fully-functional 30-day trial of Revit 2021. Simply visit the Autodesk website, create an account, download the trial, and install. After 30 days, you must purchase a subscription or uninstall.
Autodesk Revit is the industry standard for Building Information Modeling (BIM). If you need Revit 2021 specifically without paying upfront, there are legitimate ways to do so.
