What software or website do you use to build diagram?

To design a website structure I would recommend using Slickplan. Also inside sitemap pages you can create flow charts and mind maps, for example under the ‘authorization’ page cell you can draw a diagram describing the registration and signing in process for users. The diagrams can be created as a standalone, shareable and exportable projects as well.

The Slickplan web app will allow you to create beautiful diagrams. If you should need a sitemap we've got you covered too. Diagrams are now available as standalone projects, however, you'd have access to loads of tools and support that we offer. Here's a link to direct you to info about our diagram builder: https://slickplan.com/diagram Let us know if we can help! :)

Maybe this is exactly what you were looking for. I use it. And I often hear from colleagues about this service.