oday we're excited to share that Kotoba has raised an additional USD 10 million in seed funding. The round was led by Kindred Ventures, with participation from Salesforce Ventures and Sony Innovation Fund, bringing our total funding to date to USD 23 million.

Our goal is to make connecting across East Asia's languages feel effortless — to build the de facto voice AI platform for the region. This round takes us a meaningful step closer, and we'll put the funding to work accelerating exactly that.

Our Foundation Model, "Koto"

At the heart of Kotoba is our proprietary speech model, Koto — purpose-built for real-time speech applications like AI agents, smart hardware, and simultaneous speech translation, with industry-leading performance in Japanese, Korean, and Chinese.

One of Koto's strengths is how flexibly it adapts to each use case:

• It works as a speech-to-speech (S2S) model, and also as ultra-low-latency speech-to-text (ASR) and text-to-speech (TTS) models.

• It runs both in the datacenter and on-device — including on smartphones and wearables.

Three Areas We're Investing In Next

We'll direct this funding toward three priorities at the core of our voice AI platform in East Asia.

1. Speech-to-Speech (S2S)

Koto already delivers sub-2-second latency in simultaneous translation. We'll invest further in this model family, continuing to push translation quality while extending it to broader use cases such as AI agents and smart devices.

2. On-Device Rollout

Koto already runs on-device with our enterprise customers across Asia and the US. We'll dedicate more resources to running Koto efficiently on edge chips, and — together with our partners — open up wider distribution channels across automobiles, electronics, and AI wearables.

3. Agentic Rollout

We'll make the Koto ecosystem even easier to use for enterprise customers worldwide and accelerate their expansion into Asian markets. That means continuing to build out our model ecosystem, alongside hands-on forward-deployment work with our customers.

We've Released Our API / SDK

Koto is already in production with leading global organizations — from Fortune Global 500 companies to high-growth, AI-native startups — powering AI voice agents, voice interfaces for contact centers, wearable devices, and AI-powered simultaneous translation.

To put Koto in the hands of more developers, we've released an alpha version of our API and an easy-to-use Python SDK.

• Our S2S simultaneous translation models, plus ultra-low-latency speech-to-text and text-to-speech models, are now available via API.

• On-device models can also be tested through the API/SDK.

We're committed to growing the API/SDK ecosystem from here. See our API announcement for details.

Our Translation App, "Kotoba," Is Growing Fast

Koto reaches prosumers and enterprise users across East Asia through our own app, "Kotoba" (同時通訳). Built on Koto, the app delivers seamless, flagship-quality simultaneous translation, note-taking, and AI summaries — bringing real-time multilingual communication across 21 languages (with five primary target languages) to business settings as well as entertainment, tourism, and many other scenes.

In June, we shipped a major update with 11 new features and significant UI/UX improvements. We're also deepening our enterprise support, with a meeting-agent experience for remote conferences planned for July. The Kotoba app has now surpassed 180,000 users, and daily downloads keep climbing as we grow rapidly across East Asia.

Perspectives From Our Investors

We're grateful to the investors joining and supporting us in this round. Here's what they had to say.

Steve Jang, Founder & Managing Partner, Kindred Ventures

"Asia is home to nearly 5 billion people, and to start, East Asian countries represent 1.6B of that continental population. Roughly half of the world's knowledge workers speak an Asian language as their first native tongue. The complexities of getting the unique aspects of Asian languages requires a unique training strategy and learning loop approach with a deep understanding of each language and market.

The Kotoba research team brings extreme focus and depth to developing the world's fastest and most genuine speech models for both high-controllability pipelines for agents, or incredibly fast and accurate native speech-to-speech models for realtime communication and translation. On both recognition and synthesis, their Koto family of models — TTS, STT, and Speech-to-Speech — performed better than existing models developed by American and European research labs. We're thrilled to support Kotoba's mission to bring state-of-the-art speech models, multimodal agents, voice-centric wearables, physical AI hardware, and the holy grail of realtime translation to the entire world."

Ken Asada, Partner / Sho Yamanaka, Principal, Salesforce Ventures

"Under a co-founding team that combines exceptional research capabilities with strong business execution, Kotoba Technologies is developing world-class voice AI and steadily advancing its real-world implementation. In addition to their high technical capabilities, we see immense potential in their focus on driving implementation in business environments. We look forward to leveraging Salesforce's global network and expertise to support the company's further business growth."

Austin Noronha, Managing Director, Sony Ventures-US

"Real-time voice communication remains one of the most technically challenging AI frontiers. Kotoba has demonstrated impressive real-world results in both translation quality and latency, outperforming many existing approaches in speech-to-speech translation. With encouraging early product-market fit and growing adoption among enterprise customers, Kotoba is building more than a translation application, it is creating a voice AI infrastructure platform with potential applications across enterprise, telecom, electronics, and consumer markets."

Looking Ahead

East Asia's languages are spoken natively by roughly half of the world's knowledge workers — an enormous, deeply nuanced space. And real-time voice communication remains one of the hardest frontiers in AI.

We'll keep chasing the world's fastest, highest-quality voice models, working to build a world without language barriers — one step at a time. We're just getting started, and we'd love for you to follow along.