WebPAC started as Web Public Access Catalog project, but soon turned into powerful mungler for library data.
It includes input filters for CDS/ISIS, MARC and Excel, and produces MARC or entries in search engines (Hyper Estraier or KinoSearch).
Data normalization is described in small perl-like language (actually set of perl subroutines) which looks as resonable as a config file, but you have all the power which perl gives to you if you need it.
For those more down-to-earth problems, or if perl-like languages are over your head, you can also use simple modification rules to perform most quick modifications.
Primary page for this project is https://www.ohloh.net/p/WebPAC
These details are provided for information only. No information here is legal advice and should not be used as such.