docassemble is a free, open-source expert system for guided interviews and document assembly. It provides a web site that conducts “interviews” with users. Based on the information gathered, the interviews can present users with documents in PDF and RTF format, which users can download or e-mail to themselves.
Docassemble – http://docs.docassemble.org/
Built in Python. Open source, on Github at https://github.com/jhpyle/docassemble