This a great little tool! Slickmap CSS is a free, simple, stylesheet for displaying a sitemap directly from HTML unordered lists.
No software needed and includes clickable URLs.
For simple(ish) websites you no longer need Visio or similar software tools. Bonus!
Download the files from https://www.astuteo.com/slickmap
View an online demo at https://www.astuteo.com/slickmap/demo