非常に良いです。
高速。
色彩設計されていない目に痛いサイトを見ることができます。

このアドンを無効にしたり削除したあとも、白黒表示の状態です。元の色に戻りません。

一部レイアウトが崩れるサイトがあります。
例：
http s://kotobank.jp/word/晴れ-1578634

Works perfectly, even with video players. Also compatible with Dark Reader, which is a huge bonus. I normally put a greyscale filter on my phone to stop me from getting too distracted, and the same would work on my PC, but I often need colour for pdf reading. Greyscale Browsing is the easiest solution to this by just dimming out my browser and nothing else :)

Really simple and useful for concentration, also toggles grayscale for all tabs, despite what other people write.

Works great. Click on, click off. Perfect for what I need

Love the idea, thanks! But if it has to be triggered per tab then I cannot use it without a hotkey. Also doesn't work on all tabs, e.g. the one in which I'm writing this review.

I really appreciate finding this extension. Bravo! Simple, it just works and does all that is needed.
Personally trying the whole mac and mobiles in grayscale, need a quicker switch and here it is on firefox. Would appreciate customizability like colourful domains. Eg, I'd like some websites to be greyscale aside for the largest images, like booking.com, autoscout24.com/ch, comparis etc. Still, thanks for this work shared with all.
For those looking for OSX toggle: there is a script using this code https://apple.stackexchange.com/questions/196761/how-to-toggle-with-grayscale-in-yosemite saved as application and using this page to create a service to call with a keyboard shortcut: https://apple.stackexchange.com/questions/196761/how-to-toggle-with-grayscale-in-yosemite

Reading of websites with weird colors on fonts/background is much easier.

Maybe an enhanced contrast option would even improve readability?