Apps similar to Toonlight include Dark Reader, which is free and open source. Other options are Turn Off the Lights, Midnight Lizard and Night Eye. In total there are four Dark Mode Enforcers like Toonlight for iPad, iPhone, Chrome OS, Mac and Windows.
This eye-care extension enables night mode creating dark themes for websites on the fly. Dark Reader inverts bright colors making them high contrast and easy to read at night.
Russia
With a single click on the lamp button, the page will fade to dark. And automatically focus on the video. By clicking on it again, the page will return to normal. It works for all known video sites such as YouTube, Vimeo, Dailymotion, YouKu, etc.
Netherlands
EU
Midnight Lizard web-extension for Google Chrome™ and Mozilla Firefox™ provides custom color schemes for all websites.
Russia
Night Eye is a browser extension that enables dark mode on nearly any website. It does NOT simply invert the colors, but utilises a completely new approach that improves your browsing experience.
BulgariaEU
