Welcome to EDLA
This site focus essentially on automated theorem proving (ATP) or automated deduction which is a subfield of automated reasoning.
Source code is available on GitHub
If you wan't an overview of what is available on this site you can use Tags as a sitemap.
If you came thru google search due to the uniqueness of TiddlyWiki the web result you saw on google may not appear on this website. To find it just remember the query items and put on the search line to the upper right of this page. You should be able to find the item you were looking for.