Espeak

eSpeakNG is a compact open source software speech synthesizer for Linux, Windows and other platforms. It uses a formant synthesis method, providing many languages in a small size. Much of the programming for eSpeakNG's language support is done using rule files with feedback from native speakers.

Because of its small size and many languages, it is included as the default speech synthesizer in the NVDA open source screen reader for Windows, Android,Ubuntu and other Linux distributions. Its predecessor eSpeak was used by Google Translate for 27 languages in 2010; 17 of these were subsequently replaced by commercial voices.

The quality of the language voices varies greatly. In eSpeakNG's predecessor eSpeak, the initial version of each language was based on information found on . Some languages have had more work or feedback from native speakers than others. Most of the people who have helped to improve the various languages are blind users of text-to-speech.

In 1995, Jonathan Duddington released the Speak speech synthesizer for RISC OS computers supporting British English. On the 17th Feb 2006, Speak 1.05 was released under the GPLv2 license, initially for Linux, with a Windows SAPI 5 version added in January 2007. Development on Speak continued until version 1.14, when it was renamed to eSpeak.

Development of eSpeak continued from 1.16 (there was not a 1.15 release) with the addition of an eSpeakEdit program for editing and building the eSpeak voice data. These were only available as separate source and binary downloads up to eSpeak 1.24. The 1.24.02 version of eSpeak was the first version of eSpeak to be version controlled using subversion, with separate source and binary downloads made available on Sourceforge. From eSpeak 1.27, eSpeak was updated to use the GPLv3 license. The last official eSpeak release was 1.48.04 for Windows and Linux, 1.47.06 for RISC OS and 1.45.04 for Mac OS X. The last development release of eSpeak was 1.48.15 on the 16th April 2015.