Tested in French, and it's Google voice, it's very good. On my Android device, though, I've installed better voices, paying, it would be cool to be able to use Android voices with this extension, but I don't know if it would be possible one day. EDIT: I let a very good review 2 years ago, I don't know if the addon has gone less good, or if it's because I use it on a different machine, but the voice, in English or French are so so so robotic, that I can barely understand what it says.

Currently, there is still not too much fierce competition in TTS. Among all the ones that I tried, Read Aloud is the best. talkie is a half finished, product, speed adjustment is in the "coming soon" premium version, which I suppose is not free. Chirpy is a DOA. "Text to speech that brings productivity" is a godzilla for such an easy task. Firefox's own reader mode TTS is also a flop. In Japanese text, it skipped the dates and and was sluggish on words. Sentence sounds like a bag of words.

Read Aloud allows me to choose voices, such as the superior Google Japanese female voice that just rocks! She read through dates and English words in Japanese text like a local. "Macron" sounds more recognizable than any other TTS. Currently the go to TTS in my Firefox.

Best TTS extension ever used

It's Fantastic. Use full addon. It support Sinhala language also.

Cannot use this extension to read a text file from computer. I am getting this error message
"You need to grant Read Aloud access to file URLs in extension settings". But there is not such option available.

Awesome add on! Only issue is that I cannot sign in to access Premium voices.

Can't get the dang thing to work. It's Premium voices goes into a system hang blocking Firefox with a circle and a grayed screen behind the options, just telling you you have to pay for the voices without PROVIDING A WAY TO DO IT.

I use the Chrome version of this thing routinely for over a year. THIS is nothing like it, and stinks.

It's hands down the best TTS extension that I ever used. Too bad it doesn't work in private browsing mode. Hopefully it can be fixed.

I've tried more than 5 different TTS addons, but none of them functioned as well as this one. Both English and Turkish is being read alout quite well and without any hussles. The initiation and ending of the reading is very intiuitive and works just fine.
I definitely suggest trying out this addon.