Festival offers a general framework for building speech synthesis systems as well as including examples of various modules. As a whole it offers full text to speech through a number APIs: from shell level, though a Scheme command interpreter, as a C++ library, from Java, and an Emacs interface. Festival is multi-lingual (currently English (British and American), and Spanish) though English is the most advanced. Other groups release new languages for the system. And full tools and documentation for build new voices are available through Carnegie Mellon's FestVox project (http://festvox.org)

The system is written in C++ and uses the Edinburgh Speech Tools Library for low level architecture and has a Scheme (SIOD) based command interpreter for control.

English (British and American), Spanish and Welsh text to speech
Externally configurable language independent modules:
phonesets
lexicons
letter-to-sound rules
tokenizing
part of speech tagging
intonation and duration
Waveform synthesizers:
diphone based: residual excited LPC (and PSOLA not for distribution)
MBROLA database support.
distributed under a free X11-type licence
generalisation of stats modules, ngram, CART, wfst with viterbi so they can be shared more easily
Initial JSAPI support
XML load for Relations
Portable (Unix) distribution
On-line documentation
SABLE markup, Emacs, client/server (including Java), scripting interfaces.