CaptionCatch

Learn Japanese, Chinese, or English vocabulary passively while watching Videos. 100% offline, no account needed.

CaptionCatch — Vocabulary While You Watch CaptionCatch shows you a vocabulary word — reading and meaning — right on screen while you watch, picked from what's actually being said in the captions. No pausing, no clicking, no separate app to open. Just turn on captions and press play. How it works Turn on captions for the language you're learning, start watching, and relevant words appear as a small card overlay timed to the dialogue. Pick which corner (or top/bottom-center) works best for you, and CaptionCatch stays out of the way while you focus on the show. Learn what you're actually watching Japanese — JLPT-graded vocabulary (N5 through N1) Chinese — HSK-graded vocabulary (HSK1 through HSK6), supports both simplified and traditional characters English — CEFR-graded vocabulary (A1 through B2) Whichever one you're learning, see the meanings in English, German, Spanish, or French — every source language supports all four, so you can translate Japanese, Chinese, or English into whichever of those fits how you think. Built to actually teach, not just translate Words are chosen near your set difficulty level — not too easy, not overwhelming. Under the hood, CaptionCatch filters out pronouns, stray tokenizer fragments, bare numbers, and honorific name-suffixes so your review list stays full of words actually worth learning, not clutter. A short-term cooldown keeps the same word from flashing twice in a row, while a gradual repeat-deprioritization spreads out your exposure across a whole viewing session instead of overloading on one recurring word. Every dictionary lives inside the extension itself — the tokenizers, the word lists, all of it. Nothing you watch, nothing you learn, and nothing about your activity is ever sent anywhere. There's no AI involved in picking or translating words, no API calls, and no account required to use the app. Track your progress A built-in stats dashboard shows a 90-day activity heatmap, your words learned broken down by level and by language, and a full "recently learned" list you can filter and review. Free users get the full experience of watching and learning; the dashboard and deeper stats are part of Pro. Study beyond the screen Export your vocabulary straight to an Anki-ready CSV file — select individual words or grab everything at once, filtered by language if you like — so what you've learned while watching becomes real spaced-repetition study material. Misconfiguration detection, because setup issues shouldn't be a mystery If captions aren't turned on, or the caption language doesn't match what you've selected, CaptionCatch tells you directly instead of silently doing nothing. Free to start, no time limit The core experience — every source language, every goal language, every word-picking feature, full settings and customization — is free forever on YouTube, with a generous 120-word daily allowance. There's no trial countdown and no feature-crippled free tier; free users get the real product. CaptionCatch Pro unlocks: Netflix support, alongside YouTube Unlimited words per day (no 120/day cap) The full stats dashboard Anki/CSV export Pro is a simple monthly subscription — cancel anytime. Full transparency on data sources Every dictionary and word list CaptionCatch uses is either openly and permissively licensed (JLPT vocabulary data, HSK vocabulary structure, the kuromoji and jieba tokenizers, CEFR-J English vocabulary data) or generated independently for this project with no dependency on any restrictively-licensed dictionary. A "Licenses & Attribution" page inside the extension lists every source and its actual license text, pulled live from the files CaptionCatch ships with — so it's never out of date. Your privacy, respected by design CaptionCatch only reads the caption text already displayed on the video page you're watching — nothing else. It doesn't touch video playback, doesn't interact with your account, and doesn't collect or transmit any personal data, viewing history, or activity to any server. Everything happens locally in your own browser.