License Issues

EventMachine uses the Ruby License, and has it's own explicit allowance of the use of the GNU General Public License, Version 2.

The Ruby License already has this allowance, however, this is stated secondly in the licensing of EventMachine. The terms are essentially identical to that of the Ruby License, however.

As a user you are free to use the software under either license.

Some files under difference licensing terms may be packages with your distribution of EventMachine. Full details of these different licenses and files can be found in the file LEGAL that comes with the distribution.

The exact license text for the projects Ruby License can be found in the file COPYING that comes with the distribution.

A copy of the GPL v2 license text is also bundled with the distribution.

The main EventMachine source is the copyright of Francis Cianfrocca, except where otherwise stated in LEGAL.


Patches are assumed to be accepted for submission under the same licensing terms as the rest of the EventMachine distribution. Other terms must be arranged with the author.

Somebody told me that EventMachine has a really weird license

EventMachine has always had an easily-understood, standard license.

You may use EventMachine under the terms of either

Your choice.