WordByWord – Vocabulary Builder & Translator

Learn languages while reading: translate unknown words and build vocabulary on websites, YouTube subtitles & PDFs. 50+ languages.

Learn languages while you read. WordByWord turns immersion reading into a system: it shows the words you haven't learned yet, translates them in one click, and tells you — before you start — whether a page or video is at your level. 📊 COMPREHENSION LEVEL — KNOW IF IT'S AT YOUR LEVEL Stop guessing whether a video or article is too hard. WordByWord scores it against your own vocabulary before you commit your evening to it. • A real percentage of words you know — not an average "difficulty" label • Four clear zones: Easy · Your level · Challenging · Too hard • The most frequent new words, with a forecast: "These 11 words add +6% understanding" • Works on YouTube videos (from subtitles), any web article and any PDF • Learn the short word list, reopen the page — watch the number go up 🔦 SPOTLIGHT MODE — UNKNOWN WORD HIGHLIGHTING Stop wondering which words deserve your attention. Spotlight instantly reveals the words you haven't learned yet and hides the ones you already know. • Instantly highlight unknown words on any webpage • Color-coded by learning status (new → learning → known) • Update word status directly on the page • Watch your vocabulary grow over time 🌍 IMMERSION READING WHEREVER YOU READ Unlike apps that lock you into their own content, WordByWord works with the content you already care about: • Websites and online articles • YouTube subtitles • PDFs (local and online files) • Blogs, news, books, research papers 📺 YOUTUBE LEARNING • Turn any video into a language lesson • Click any subtitle word to translate and save it • Auto-pause on hover • Navigate by subtitles, not seconds • See a comprehension score for the video before you play it 📄 PDF TRANSLATOR • Translate words directly inside the document — a built-in dictionary for any PDF • Perfect for books, textbooks and research papers • Works with local and online files • Coverage is scored page by page as you read 🎯 VOCABULARY TRAINER • Multiple training modes • Smart spaced repetition • Train only the words you actually need • Review with flashcards • Import and export your vocabulary (Anki, CSV, PDF) • See how well you know each word 🌎 50+ LANGUAGES French, Spanish, German, Japanese, Korean, Italian, Portuguese, Chinese, Arabic, Russian and many more. The comprehension score works in every language you learn — it compares content against your vocabulary, not against English. 💡 HOW PEOPLE USE IT • Picking a series: score the first episode of three candidates, start with the one in your level • Filtering a reading list: let the new-words count sort your saved articles • Getting through a textbook: learn the frequent words first instead of abandoning it at page 20 • Studying with YouTube: click subtitle words, then review them without leaving the browser 🚀 WHY WORDBYWORD? Unlike basic translators, WordByWord helps you: ✓ See which words you know and which you don't ✓ Know in advance whether content is at your level ✓ Build your vocabulary faster with real content ✓ Track your progress visually ✓ Focus only on the words you still need to learn ✓ Keep learning wherever you read Free to start — translations, saved words and collections have no limits. Install → Turn on Spotlight → Grow your vocabulary