Hear it. Read it.
Instantly.
Kotoo turns podcasts, videos and live streams into word-synced bilingual subtitles as you listen. Every word lights up with the voice — and anything unfamiliar is a single tap from making sense.
Bilingual subtitles that keep pace with the voice
From a new podcast episode to a YouTube video or a live news broadcast, Kotoo transcribes and translates while you listen. Original and translation arrive almost together — no waiting for an entire episode to process.
- Built for live broadcastsEnglish news and finance channels, subtitled line by line as the anchor speaks.
- Generated as you playJump anywhere, and the subtitles for that moment fill in right away.
- A layout made for listeningOriginal above, translation below, with the current line always in focus.
Every word, perfectly in time
Word-aligned transcripts light up the text at the speaker's pace. Readings, glosses and part-of-speech marks appear on demand, and the layout never shifts during playback — so your eyes can stay put.
- Precision to the wordThe word being spoken is highlighted the instant you hear it.
- Readings and meanings alongsideToggle kana, romaji and glosses independently to set your own level.
- Listen first, then readMask words not yet spoken and train genuine listening before you check.
Tap a word. Understand it.
Look-up cards show the dictionary form, reading and meaning — and what the word means in this exact sentence. For complex lines, AI explanations unpack grammar and idiom layer by layer.
- Meaning in contextNot just dictionary senses, but the sense that fits this line.
- AI sentence breakdownsGrammar, nuance and usage, explained one sentence at a time.
- Replay the originalHear the line again as you look it up, tying meaning to sound.
Make what you understand stick
Save new words with their original sentence and audio, then review them on a schedule shaped by how memory works: hear the line first, recall the meaning second. Shadow each sentence against the original to sharpen listening and speaking together.
- A word book with real audioEvery entry keeps the sentence and the voice it came from.
- Spaced, active reviewWords return just before you would forget them — recall, not rote.
- Sentence-by-sentence shadowingRecord yourself and compare your rhythm with the original waveform.
The shows you love are the best textbook
Start straight away with curated podcasts, videos and live channels — or import Apple Podcasts, RSS and YouTube links to turn what you already enjoy into study material. Japanese and English are supported today.
- Curated podcasts
- YouTube videos
- Live news
- Apple Podcasts
- RSS feeds
- Japanese · English
The core experience is free
Curated content and every learning feature are free to use. Membership adds generous transcription time for your own imports and more AI explanations — for learners who study at volume.
Free
Start instantly, no sign-up
- Unlimited listening to curated podcasts, videos and live channels
- Word-level subtitles, look-ups, word book and shadowing
- Monthly transcription time for your own shows
- A daily allowance of AI explanations
Membership
For dedicated learners
- Everything in Free
- More transcription time for your own imports
- More AI explanations
- Monthly or yearly — cancel anytime
Kotoo is coming to the App Store
We're putting the finishing touches on launch. When it arrives, start with your favourite show.