It uses the Audio API and a Text-To-Speech service to read website text on click on it.
Additionaly, it enhances contrast of images using Canvas post-processing (thanks to Pixastic library, under Mozilla Public Licence).
To toggle reader on/off click to speaker icon on extensions toolbar. If turned on you need to click on text paragraph and wait to audio.
This extension will use build in (in Chrome) speech engine so it may not be available in your native language.