Is Mibble “free” software?
Yes, Mibble is free software (software libre) according to the Free Software Definition. It is publicly distributed under the GNU General Public License (GPL). No, Mibble is not free in the sense that you may do with it as you wish. The GNU GPL explictly limits the redistribution of Mibble and any derived work in several ways. In particular, if your program requires Mibble to run, it must also be distributed under the GNU GPL. As an alternative to using the GNU GPL, a non-exclusive commercial license for Mibble can be purchased.