eSpeak is a compact open source software speech synthesizer for English and other languages, for Linux and Windows.Discontinued
The last version (1.48) is from March 2014.
Verbify-TTS is a simple Text-to-Speech (TTS) engine that reads for you any text on your screen with high-quality voices powered by AI models. It is free and you can use it for unlimited time (Open Source MIT LICENSE).
Acapela Group, the leading European voice expert leaning upon 25 years of experience, invents text-to- speech solutions to give your content a voice in up to 25 languages. Our speech solutions allow you to turn any written text into natural speech files, using any of the 50 High...
Fala - A simple text reader is an open source application. A simple software that speaks a text. You can type the text or appoint a file. Fala is just a frontend to festival. Its designed for GNOME, but if you have gtk, pyhton and festival you are able to run it.
Speech Services provides speech-to-text functionality to Google and other third party apps to convert what you say to text.