How to Install a Revit Add-in
To install a Revit add-in manually: copy the .addin manifest and the DLL it references into %AppData%\Autodesk\Revit\Addins\<version>\. Restart Revit. The add-in appears as a new ribbon tab or as commands under External Tools. Most commercial add-ins ship an installer that does this automatically.
Steps
Close Revit
Revit only scans the Addins folder at startup. Any add-in dropped while Revit is running is ignored until restart.
Find your Addins folder
Per-user: %AppData%\Autodesk\Revit\Addins\<version>\ (e.g. 2025). Machine-wide: %ProgramData%\Autodesk\Revit\Addins\<version>\. Use per-user unless you need every user on the PC to get it.
Drop in the files
Copy both the .addin manifest and the .dll into the Addins folder. Some add-ins ship a subfolder of dependencies — keep them together. The .addin must reference the DLL by relative path.
Open Revit and verify
Launch Revit. Open a project. Look for a new ribbon tab from the add-in, or check Add-Ins tab → External Tools.
Activate the license
On first command run, most commercial add-ins prompt for a license. Enter the order ID and email from your purchase.
Frequently asked questions
Revit says the add-in is not signed. Should I trust it?
Revit warns on first load of any unsigned add-in. If you bought from a verified seller (CAD Exchange, Autodesk App Store, etc.) you can click 'Always Load'. Decline anything from an unknown source.
Why isn't the add-in appearing on the ribbon?
Open Add-Ins tab → External Tools. If the commands appear there but not on a ribbon tab, the add-in's author chose not to create a ribbon tab (some add-ins are command-only). If they don't appear in External Tools either, the .addin manifest didn't load — check the path and the AddInId GUID for uniqueness.
Where is %AppData%?
Press Win+R and type %AppData% then Enter. It opens to C:\Users\<you>\AppData\Roaming\. Autodesk\Revit\Addins\<version>\ is inside there.
Will the add-in survive a Revit version upgrade?
No. Revit add-ins are version-locked. Upgrading from 2024 to 2025 means dropping the 2025 build into the 2025 Addins folder. Reputable vendors maintain builds for every supported Revit version.
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Related terms
The XML file Revit reads at startup to discover and load .NET add-ins from the user's Addins folder.
The Revit .NET interface a class implements to expose a single command button. Implements Execute(...) and returns Result.Succeeded/Failed.
Autodesk's Building Information Modeling (BIM) authoring tool. Automated primarily with Dynamo and the Revit .NET API.
A managed assembly (C#/VB.NET DLL) that uses Autodesk's .NET API to add commands and behaviour to AutoCAD or Civil 3D.