In 1991 and 1992, Tim Berners-Lee and a student at CERN named Jean-François Groff rewrote various components of the original WorldWideWeb browser for the NeXTstep operating system in portable C code, in order to demonstrate the potential of the World Wide Web. In the beginning libwww was referred to as the "Common Library" and was not available as a separate product. Before becoming generally available, libwww was integrated in the CERN program library (CERNLIB). In July 1992 the library was ported to DECnet. In the May 1993 World Wide Web Newsletter Berners-Lee announced that the Common Library was now called libwww and was licensed as public domain to encourage the development of web browsers. He initially considered releasing the software under the GNU General Public License, rather than into the public domain, but decided against it due to concerns that large corporations such as IBM would be deterred from using it by the restrictions of the GPL. The rapid early development of the library caused Robert Cailliau problems when integrating it into his MacWWW browser.