The Kotojutsu extension for Chrome and Firefox
Read Japanese on any website: a word's meaning appears on hover, and one click adds it to your Kotojutsu cards. Free, with the same account as the site.
On Edge, Brave, Opera or Vivaldi, use the Chrome Web Store. Safari and phones are not supported.
What it does
Meanings on hover
Hold Shift and hover over Japanese: reading, meaning, JLPT level, and the form it recognised (食べなかった → 食べる, past negative). The key can be changed.
One click to review
"Add" puts the word in the deck of your choice, with the sentence you read it in. It then comes back in your flashcards, on the site and in the app.
Japanese subtitles
On YouTube, Japanese subtitles appear in a strip where you can hover each word; the video pauses while you read. A .srt, .ass or .vtt file works on any video.
Voice and search
Hear the word with the voice chosen in your account, look up a selected word (right-click or Alt+K), and see your streak and cards to review in the extension's window.
Your privacy
The dictionary lives in the extension: hovering a word sends nothing, neither the word nor the page you read, and your history is not recorded. Only the words you add or look up reach Kotojutsu, with your session if you are signed in. Privacy policy.