SHTSoft respects your privacy and collects only a minimal amount of data.
The webserver - lighttpd - writes logs according to its default error.log and access.log. I.p., this comprises IP addresses, timestamps, referrers and user agents. The collected data is only used for debugging purposes in case of failure and is not used for anything else. It is kept around for at most two months.
Furthermore note that some pages of the site use mathjax for rendering mathematical formulas. This does, however, not have any privacy implications.