Publicitas run a project named NACA from 2003 to 2007. It successfully ended with the recurring yearly  savings of 4.5 Mio CHF in opex.

It was all about migrating an IBM mainframe with a homegrown transactional application (1'300+ users)  to Linux & Java on Intel servers.

During this migration we developped our own tools to 100% automatically migrate & test our 4 millions of lines of Cobol to Java. We have now opensourced them and they are being used by other companies for their ownequivalent project. They've now been downloaded 520+ times.