Spoiler words are replaced by the string containing "*" s of equal length.
User can add and remove sopiler words of his choise at any time from the extension popup, and also by selecting any word from webpage user will get an option in context menu to add that word in the list of spoiler words.
User can remove a word by selecting it from the drop-down available in extension popup, and also if user selects a sting containing "*" s of some length he will be shown spoiler words of same length in context menu option, so he can directly delete it from there.
User must refresh the page to be able to reflect the changes on webpage, i.e. to hide newly added words and unhide newly removed words.
User can whitelist a website meaning, all webpages from whitelisted website will be exempted from hiding spoiler words.
To add and remove a website from whitelist user can use extension popup in similar way as mentioned in previous feature.
User is notified after masking spoiler words showing how many words have been masked, after adding and removing words from spoiler list and websites from whitelist. However user has an option or enable and disable notifications, it can be found in extension popup.