It's undocumented but it wouldn't be hard to add. Essentially you blacklist a domain in the 3 dot menu (toolbar icon on desktop). Blacklisted sites will show a word and key-value pairs of letters and numbers, you have to add up the values for each letter in the word to unlock the page. You can change the word length in the options page, also in options you can set the extension to sleep for 5, 15, and 30 minutes when you want to disable it without having to later re-enable it.
It's undocumented but it wouldn't be hard to add. Essentially you blacklist a domain in the 3 dot menu (toolbar icon on desktop). Blacklisted sites will show a word and key-value pairs of letters and numbers, you have to add up the values for each letter in the word to unlock the page. You can change the word length in the options page, also in options you can set the extension to sleep for 5, 15, and 30 minutes when you want to disable it without having to later re-enable it.