ufdbguardd is a URL filter for the Squid web proxy. Squid does not use the term URL filter but the term URL rewriter.
ufdbguardd is normally not called from the command line but from a system initialisation script.
There exists an extensive Reference Manual for ufdbGuard with sections for installation and configuration.
ufdbgclient(1), ReferenceManual_1_35.pdf, https://www.urlfilterdb.com/downloads/software_doc.html.
ufdbGuard 1.0 was based on squidGuard 1.2.0. Some code of the original squidGuard was removed while a lot of code was added by URLfilterDB.
The developers of URLfilterDB - https://www.urlfilterdb.com
The developers of squidGuard 1.2.0.