eSpeak NG
FreeA few megabytes, over a hundred languages, reading aloud with no network
Open Source No Ads No Tracking Offline No Sign-up Cross-platform
A compact formant-synthesis speech engine covering more than a hundred languages and accents in a few megabytes, running on very low-powered hardware. The voice is plainly synthetic; the strengths are size, speed, language coverage and being entirely offline. It is the engine underneath many screen readers.