Oops, I accidentally learned Japanese.

Field notes

The learning loop operates inside pages the reader is already browsing: words are replaced gradually, difficult items return sooner, and a gold bar indicates how much of a line is readable. The page lists 2,022 vocabulary words, 1,020 kanji, furigana and romaji support, JLPT levels N5–N1, and offline operation in Chrome and Edge. Optional export supports moving an accumulated vocabulary list elsewhere, while cross-browser syncing is described as a one-time $25 purchase.