Draw.io is a popular online diagramming tool that offers a wide range of features and templates. It's free to use, and you can create diagrams directly in your web browser.
Further research could involve a detailed usability study of these tools, exploring their capabilities in specific professional domains, and developing criteria for selecting the most appropriate tool based on user needs. free visio link
Microsoft doesn’t offer a permanent free version of Visio, but you can get Visio for the web free for 30 days: free visio link
Once you paste this code into your website, any visitor can pan and zoom the Visio diagram without ever knowing what a .vsdx file is. free visio link