These are fully stand alone. Downloadable. So not strictly hosted I guess?
Does it need to be “hosted”?
I like both these:
yEd (https://www.yworks.com/products/yed)
Dia Diagrams (http://dia-installer.de)
I think yEd had a free version but closed source.
You might find some starting points or even projects or terms to look for in this article:
This worked well for me and it gave me a spreadsheet (.csv) of my posts and comments.
You just go to the linked page, drag the “button” up to your bookmarks bar. Then navigate to your reddit profile and click the bookmark let, select your options and “go” - then wait.
Mine took about 15 minute to scrub 10 years and about 2000 comments. It missed a few so I manually edited and then deleted those.
Take note… I’ve heard (anecdotally), if you want your history backup, do not interrupt the process or close the window.
Lol… Well I’m glad someone saw it :D