Verdict: Essential, but increasingly difficult to source.
Addins (2018) folder before installing any third-party extension.Autodesk Account (Manage): Sign in to your Autodesk Account and navigate to "Product Updates." Look for "Add-ons" or "Extensions" specifically filtered for the 2018 version. download revit extensions for autodesk revit 2018 best
Important Note Before You Start:
Autodesk no longer offers a single, unified “Revit Extensions” installer for Revit 2018. Most of those tools have been either: Review: The Hunt for the Best Revit 2018
Best for: Data interoperability
For new downloads, you must rely on: