"microsoftofficetoolscommonv90" refers to a specific version of the Microsoft Visual Studio Tools for Office (VSTO) Runtime
: If you are a developer, the best way to get this is by installing the "Office/SharePoint development" workload within Visual Studio 2019 or 2022 . This ensures all "Common" libraries are correctly registered in your Global Assembly Cache (GAC). How to Install and Troubleshooting microsoftofficetoolscommonv90 download 2021
: Modern Office 2021 development should use newer libraries. If you must use v9.0, ensure you have the Visual Studio 2008 If you must use v9
: Consider moving to Office 2024 or Microsoft 365 for improved performance and long-term security. If you must use v9.0
: Links claiming to provide this specific file as a "2021 download" (especially in ZIP format from third-party sites) are frequently associated with malware or unauthorized "cracked" software distributions.
Here is a full guide on what this file is, why you might need it, and how to safely install it in 2021 and beyond.