How to Register a SOLIDWORKS Add-in DLL (64-bit)
- Authored by Amen Jlili
- Updated June 10, 2025
- Published
- Topics covered: solidworks api
- Be the first to share your thoughts.
Disclaimer: This only works for old legacy .NET framework 2, 3 and 4.
If you’re developing a SOLIDWORKS add-in using the .NET Framework (No later than 4), you will need to register your DLL. This process ensures that SOLIDWORKS can discover and load your add-in correctly.
You can do this automatically in Visual Studio, but that will be covered in a different article.
Step-by-Step Instructions (64-bit or Any CPU)
- Open Command Prompt as Administrator
- Navigate to the output folder of your compiled DLL:
cd <DLL FOLDER>.dll - Run the 64-bit .NET registration tool:
C:\Windows\Microsoft.NET\Framework64\v4.0.30319\RegAsm.exe /codebase <DLL FILENAME>.dll - If successful, you’ll see:
Types registered successfully 
Warning: You may also get this message: “Registering an unsigned assembly with /codebase can cause your assembly to interfere with other applications…”
This is normal in development. In production, you should sign your assembly with a strong name key.
What About 32-bit Registration?
You can also register a 32-bit DLL using:
But unless you’re targeting SOLIDWORKS 2013 or earlier, there’s no need to register 32-bit DLLs. All modern versions of SOLIDWORKS run as 64-bit applications, and your add-in must match that architecture.
Unregistering the Add-in
If you need to remove the add-in (e.g., you’re cleaning up or switching between builds), run:
Still Need Help?
At Blue Byte Systems, we build and maintain professional SOLIDWORKS add-ins for automation, analysis, UI enhancements, and system integration. If you’re running into issues or need a reliable API resource, we’d be happy to help.
