The compiler is free for any use and the existing library of functions on this page is open source, but the source code of compiler is not released.
http://www.telefonica.net/web2/emilioguerrero/CPCBasic/CPCBasic.html (URL inaccessible since 2012, [http://web.archive.org/web/20120208115405/http://www.telefonica.net/web2/emilioguerrero/CPCBasic/CPCBasic.html Web Archive])