Common interface to speech synthesis


This is the Speech Dispatcher project (speech-dispatcher). It is a part of the Free(b)soft project, which is intended to allow blind and visually impaired people to work with computer and Internet based on free software.

Speech Dispatcher project provides a high-level device independent layer for access to speech synthesis through a simple, stable and well documented interface.


Complete documentation may be found in doc directory. Read doc/README for more information. This documentation is also available online.

The SSIP communication protocol is also documented.

The key features and the supported TTS engines, output subsystems, client interfaces and client applications known to work with Speech Dispatcher are listed in overview of speech-dispatcher as well as voices settings and where to look at in case of a sound or speech issue.


There is a public mailing-list for this project.

This list is for Speech Dispatcher developers, as well as for users. If you want to contribute the development, propose a new feature, get help or just be informed about the latest news, don't hesitate to subscribe. The communication on this list is held in English.


Various versions of speech-dispatcher can be downloaded from the project archive.

Bug reports, issues, and patches can be submitted to the github tracker.

The source code is freely available. It is managed using Git. You can use the GitHub web interface or clone the repository from:

A Java library is currently developed separately. You can use the GitHub web interface or clone the repository from:

To build and install speech-dispatcher and all of it's components, read the file INSTALL.


Speech Dispatcher is being developed in closed cooperation between the Brailcom company and external developers, both are equally important parts of the development team. The development team also accepts and processes contributions from other developers, for which we are always very thankful! See more details about our development model in Cooperation. Bellow find a list of current inner development team members and people who have contributed to Speech Dispatcher in the past:

Development team:

  • Samuel Thibault
  • Jan Buchal
  • Tomas Cerha
  • Hynek Hanke
  • Milan Zamazal
  • Luke Yelavich
  • C.M. Brannon
  • William Hubbs
  • Andrei Kholodnyi

Contributors: Trevor Saunders, Lukas Loehrer,Gary Cramblitt, Olivier Bert, Jacob Schmude, Steve Holmes, Gilles Casse, Rui Batista, Marco Skambraks ...and many others.


Copyright (C) 2001-2009 Brailcom, o.p.s Copyright (C) 2018 Samuel Thibault Copyright (C) 2018 Didier Spaier

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details (file COPYING in the root directory).

You should have received a copy of the GNU General Public License along with this program. If not, see


  • The speech-dispatcher server (src/server/ + src/common/) contains GPLv2-or-later and LGPLv2.1-or-later source code, but is linked against libdotconf, which is LGPLv2.1-only at the time of writing.

  • The speech-dispatcher modules (src/modules/ + src/common/ + src/audio/) contain GPLv2-or-later, LGPLv2.1-or-later, and LGPLv2-or-later source code, but are also linked against libdotconf, which is LGPLv2.1-only at the time of writing.

  • The spd-conf tool (src/api/python/speechd_config/) and spd-say tool (src/clients/say) are GPLv2-or-later.

  • The spdsend tool (src/clients/spdsend/) contains both GPLv2-or-later and GPLv2-only source code.

  • The C API library (src/api/c/) is LGPLv2.1-or-later

  • The Common Lisp API library (src/api/cl/) is LGPLv2.1-or-later.

  • The Guile API library (src/api/guile/) contains GPLv2-or-later, LGPLv2.1-or-later, and LGPLv2.1-only source code.

  • The Python API library (src/api/python/speechd/) is LGPLv2.1-or-later.

  • src/tests/spd_cancel_long_message.c and src/tests/spd_set_notifications_all.c are GPLv2-only.

  • other tests in src/tests/ are GPLv2-or-later.