- Firefox OS to be supported initially by 18 carriers, first official devices announced Mozilla is quick out of the gate at Mobile World Congress 2013 as the company announces a number of important updates to its HTML5-only operating system - Firefox OS - and, most notably, a list of 18 carriers that have pledged their commitment to the ambitious project.
- Thunderbird email client gets shelved, sort of Mozilla will no longer be releasing feature updates to its open-source email client Thunderbird, but instead will focus on products that provide a "source of innovation and of leadership in today's internet life" - like Firefox OS.