MultiPar consists of PAR clients and GUI to control them. They are written by Yutaka Sawada. Though console applications are open source (PAR clients are GPL), GUI application is closed source. Some article are available at my web site. There are source code packages on GitHub.
  I use GitHub issue's page as a web-forum for MultiPar users.
  My name is Yutaka Sawada. E-mail address is "tenfon (at mark) outlook.jp". Or "multipar (at mark) outlook.jp" for PayPal usage and "tenfon (at mark) users.sourceforge.net" for SourceForge users. Because they use a same mail-box, don't send duplicate mails. Though e-mail address had been "ten_fon (at mark) mail.goo.ne.jp" ago, the mail service ended at March 2014, so don't send to there. The (at mark) is format to avoid junk mails, and replace it with "@".
  I get many spam mails from oversea. If an e-mail is detected as junk mail or suspicious, mail server may delete it automatically, and I won't see it.
  I use vector.co.jp's author page to introduce MultiPar. Because there is another official download page, using direct link to files on the page isn't preferable. When you write a link on somewhere, please don't include filename.