fcitx is described as 'Fcitx ['fa?t?ks] is a input method framework with extension support. Currently it supports linux and Unix system, like freebsd. It has three builtin Input Method Engine, Pinyin, QuWei and Table-based input methods'. There are three alternatives to fcitx for Linux, Mac and BSD. The best alternative is iBus, which is both free and Open Source. Other great apps like fcitx are UIM (Free, Open Source) and scim (Free, Open Source).
The Smart Common Input Method (SCIM) platform project provides not only a user friendly, full featured input method user interface for POSIX-style operating systems (including Linux, FreeBSD and other Unix), but also a development platform to make input method development easier.