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.
See every word. Understand every line.
Word-aligned transcripts light up at the speaker’s pace, with readings, glosses and phrase grouping on demand. Tap any unfamiliar word to look it up, and let AI unpack the complex lines — from hearing to understanding in one flow.
- Precision to the wordThe word being spoken is highlighted the instant you hear it.
- Readings, glosses and phrasesToggle kana, translations and colour-coded phrase groups to see how each sentence is built.
- Listen first, then checkMask words not yet spoken, understand by ear, then confirm against the subtitles.
- Tap to look up, ask AILook-up cards give the meaning in this very sentence; AI breaks down grammar and usage in longer lines.
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.