dynamic invApp = System.Activator.CreateInstance("Inventor.Application"); // late binding invApp.Documents.Add(kPartDocumentObject); // no type safety, harder to release.

Click and navigate to the Public Assemblies folder in your Inventor installation directory. Select Autodesk.Inventor.Interop.dll and click OK . Set the Embed Interop Types property:

The following production-ready C# example demonstrates how to safely connect to an active session of Autodesk Inventor or spin up a new instance if it isn't running.

.NET uses Garbage Collection, whereas COM relies on reference counting. If your code leaves references to Inventor objects open in memory, the inventor.exe process will remain running in the Windows Task Manager even after the user closes the application interface.

using Inventor; // Exposes the Application, Documents, and PartDocument classes Use code with caution. Code Blueprint: Connecting to Inventor

The top-level object in the API hierarchy. It represents the running Inventor instance. You use this to create new parts, open existing assemblies, or access application-wide settings. 2. Document Objects The API breaks down files into specific object types: PartDocument AssemblyDocument DrawingDocument 3. Geometry and Modeling

Right-click in Solution Explorer and select Add Reference .

Last updated: October 2025 – compatible with Inventor 2024 and 2025.

When building an application, you should navigate to this path to add the reference to your Integrated Development Environment (IDE) like Visual Studio. How to Use It in Visual Studio (C# Example)

For instance, the Interop DLL is a required reference when creating user interface tools for an Inventor add-in, ensuring that the custom UI can properly interact with the CAD environment. It effectively translates the Inventor.Application object from Inventor's world into a class that a C# or VB.NET project can work with.

try

Autodesk Inventor is built largely on Microsoft's Component Object Model (COM) technology. The .NET framework, which is commonly used for modern customization (C#, VB.NET), cannot directly "talk" to COM components.

This is one of the most persistent challenges when working with autodesk.inventor.interop.dll . The interop assembly generally has the same version as Inventor's type library. When you build an add-in with Inventor 2020 (say version 24.0) and a user tries to run it with Inventor 2025 (version 29.0), you may encounter a System.IO.FileLoadException .

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