Here is a non-exhaustive comparison of speech synthesis programs:
General
Name Creator(s) First public release date Latest stable version Software license 15.ai 15 2020 2025 Apple PlainTalk Apple Inc. 1984 2018 Bundled with Mac OS X AT&T Natural Voices AT&T Natural Voices 2008 Proprietary PollyAmazon AWS 20162019Proprietary Cepstral Cepstral 2000 2013 Proprietary CereProc CereProc 2006 2017, February Proprietary eSpeak Jonathan Duddington 2006, February 10 2022, April 3 GPLv3+ Festival Speech Synthesis System CSTR 2014, December MIT-like license FreeTTS Paul LamerePhilip KwokDirk Schnelle-WalkaWillie Walker... 2001, December 14 2009, March 9 BSD LumenVox LumenVox 2011 2019 Proprietary Microsoft Speech APIMicrosoft19952012Bundled with Windows VoiceText ReadSpeaker (Formerly Neospeech) 2002 2017 Proprietary Nuance Vocalizer Nuance Communications, Inc. 2018 Proprietary Typecast (AI voice generator) Neosapience 2019 2025, September Proprietary
Technical voice details
Platform SSML SAPI version WS PLS CLI 15.ai Apple PlainTalk AT&T Natural Voices 5.1 Cepstral (company) 5.x CereProc 5.x eSpeak 5.x Festival Speech Synthesis System FreeTTS LumenVox 5.x Microsoft Speech API 4.x/5.x Nuance Vocalizer VoiceText 5.x
Technical details
Name Online demo Available language(s) Available voices Programming language Operating system(s) 15.ai English (United States) 50+ Python Any Apple PlainTalk English (United States), ... 15+ Macintosh AT&T Natural Voices English (British), English (Indian), English (US), French, French (Canadian), German, Italian, Spanish (Latin American) 20 C++ LinuxWindows Cepstral English (British), English (US), Italian, French (Canadian), German, Spanish (American), ... 25+ C/C++ Mac OS XWindowsi386-Linuxx86-64-LinuxSparc-Solarisi386-Solaris CereProc English (British), English (US), English (Scottish), English (Irish), French, French (Canadian), German, Austrian German, Italian, Irish, Spanish (Castilian), Spanish (Latin American), Dutch, Polish, Portuguese, Portuguese (Brazilian), Japanese, Catalan, Scottish Gaelic, Swedish, Russian, Mandarin 46 Java / C C++ / Objective C / Python / C# & .Net through SAPI LinuxWindowsMac OS XEmbedded LinuxAndroidiOSCloud service eSpeak Samples Afrikaans, Albanian, Armenian, Cantonese, Catalan, Croatian, Czech, Danish, Dutch, English (British, US, Scottish, Westindies...), Esperanto, Estonian, Finnish, French (France, Belgium), Georgian, German, Greek, Hindi, Hungarian, Icelandic, Indonesian, Italian, Kannada, Kurdish, Latvian, Lojban, Macedonian, Malayalam, Mandarin, Norwegian, Persian, Polish, Portuguese, Romanian, Russian, Serbian, Slovak, Spanish, Swahili, Swedish, Tamil, Turkish, Vietnamese, Welsh. several C++ LinuxWindowsMac OS XRISC OS Festival Speech Synthesis System English (UK), English (US), Spanish, Hindi, Croatian, Finnish, Polish, Welsh. Several C++ LinuxWindows FreeTTS English... Several Java Cross-platform LumenVox Danish, Dutch, English (Australian), English (US), English (UK), English (Welsh), English (Indian), French, French (Canadian), German, Icelandic, Italian, Polish, Portuguese, Portuguese (Brazilian), Romanian, Russian, Spanish (North American), Spanish (Latin American), Spanish (Castilian), Swedish, Turkish, Welsh, Welsh English 57 C/C++ WindowsLinux Nuance Vocalizer US English, Australian English, Indian English, Irish English, South African English, UK English, Argentinian Spanish, Castilian Spanish, Colombian Spanish, Mexican Spanish, Arabic, Catalan, Basque, Galician, Dutch, Belgian Dutch, Portuguese, Brazilian Portuguese, Bulgarian, French, Canadian French, Cantonese (Hong Kong), Mandarin, Mandarin Taiwanese, Czech, Danish, Finnish, German, Greek, Hebrew, Hindi, Hungarian, Indonesian, Italian, Japanese, Korean, Norwegian, Polish, Romanian, Russian, Slovak, Swedish, Thai, Turkish 70+ C/C++ WindowsLinuxAndroid VoiceText English (US), English (British), American Spanish, Canadian French, Chinese Mandarin, Japanese, Korean 13 C/C++/Java WindowsLinux