There’s also this: https://github.com/GhostText/GhostText
From my friends feedback, it is more maintained and less buggy; YMMV. (I’ve never tried this one)

2019. 5. 11. 오후 3:13, Eli Zaretskii <eliz@gnu.org> 작성:

>> From: Óscar Fuentes <ofv@wanadoo.es>
>> Date: Fri, 10 May 2019 23:12:08 +0200
>> 
>> It is possible to use Emacs to write text areas on web pages with an
>> extension. You enter the text area and with a key combination (1)
>> emacsclient is invoked. Those of us that are mouse-averse can use
>> extensions that make possible to click links, buttons, etc using the
>> keyboard, it is much more efficient than the mouse. There are more
>> possibilities to make the web less painful, it is just a matter of
>> installing two or three extensions and that takes no time if someone (2)
>> points you to the right place.
> 
> With which browsers is this possible?  Any further details about such
> extensions?
> 
> Thanks.
>