Kotoba
Frontier speech AI · Tokyo & SF

Ever worked with someone who doesn’t speak your language natively?

Kotoba builds voice AI models and products so you can communicate with anyone in real time.

English 日本語 한국어 中文
The foundational voice AI model for a borderless world
Kotoba
Products

We ship our own frontier speech models.

For teams
Meeting tool
Multi-language meetings with live translated voice and captions — everyone speaks their own language.
EN ⇄ JA ⇄ KO ⇄ ZH
For everyone
Kotoba App
A simultaneous interpreter in your pocket — real-time voice and text, no delays.
iOS · Android
For builders
Koto models
Frontier ASR, TTS and speech-to-speech translation models, licensed to companies.
sub-50 ms TTSon-prem · on-device
02 / 07
Kotoba
Your presenters

Four people, the whole stack — research to app.

Yuta Sasaki
Yuta Sasaki
Founding ML Engineer
Qian Cheng
Qian Cheng
Machine Learning Engineer
Jaeeon Park
Jaeeon Park
NLP Researcher
Justin Garcia
Justin Garcia
Full Stack Application Engineer
03 / 07
Kotoba
How we train · Qian Cheng

How we train Koto.

1
Data
Millions of hours of paired multilingual speech.
2
Pretrain
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3
Fine-tune
Paired speech teaches translation.
4
Align & evaluate
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Example shown: speech-to-speech translation models
04 / 07
Kotoba
How inference works · Yuta Sasaki

We start translating before you finish your sentence.

Step 1
Listen
Audio streams in as small chunks.
Step 2
Encode
Chunks become audio tokens instantly.
Step 3
Translate
The decoder commits words as confidence lands.
Step 4
Speak
Their language — and coming soon, your voice (cloning).
⟶ Placeholder: Sasaki-san adds real latency numbers & serving details here.
05 / 07
Kotoba
Working at Kotoba · Jaeeon Park

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Small team, total ownership — the model you train ships in the app.
We dogfood daily — our own meetings run through Kotoba.
Research goes to production in weeks, not quarters.
06 / 07
Kotoba
Careers

Help us build a borderless world — we’re hiring.

AI Researcher San Francisco
Speech Edge AI Researcher Tokyo & SF
Full-Stack Engineer Tokyo
Infrastructure Engineer Tokyo & SF
Technical Account Manager Tokyo & SF
more GTM · Comms · Partnerships
site.kotoba.tech/company#careers Talk to any of us after ⟶