Genki/WaniKani Kanji Highlighter

Conveniently highlights kanji on the currently viewed webpage based on two learning sources: WaniKani and Genki textbook series. Red kanji will be learned in more than 5 levels/chapters, Yellow kanji will be learned in 5 levels/chapters or less, and Green kanji are already learned (the lighter green corresponds to kanji learned farther in the past). Grey kanji do not appear in either learning source.

Automatically updates WaniKani level given your account's API key (can be found on WaniKani -> Settings -> Account).
Saves API key to local browser storage (so you only have to input it once).
Can be used for only a single learning source, simply disable Genki or do not enter an API key.