Kotoba Technologies Raises $10M in Additional Seed Funding

The round also saw participation from Salesforce Ventures and Sony Innovation Fund.

The company plans to use the funding to improve its speech-to-speech (S2S) models, make its software more efficient for edge computing chips, and expand its global deployment infrastructure in East Asian enterprise markets.

Kotoba’s main model, Koto, is designed for real-time speech applications like AI agents, smart devices, and live translation. It performs especially well in Japanese, Korean, and Chinese, with strong accuracy and speed.

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Koto is already being used by major global organizations, including Fortune 500 companies and fast-growing AI startups. In these deployments, it powers AI voice agents, contact center voice tools, wearable devices, and real-time translation.

To make the technology more accessible, Kotoba has launched an alpha API and a simple Python SDK for developers. Its speech-to-speech translation models, as well as low-latency speech-to-text and text-to-speech models, are available through the API, and on-device models can also be tested. Kotoba plans to continue expanding its API and SDK ecosystem.

Kotoba’s app, Kotoba (同時通訳), is widely used by prosumers and enterprise users across East Asia. Built on its proprietary model, it offers real-time translation, note-taking, and AI summaries.

The app supports 21 languages and is used in business, travel, tourism, and entertainment. In June, Kotoba released a major update with 11 new features and improved UI/UX. The company is also preparing a meeting-agent feature for remote conferences, expected in July. The app has now reached over 180,000 users, with daily downloads still increasing.

Steve Jang, Founder & Managing Partner, Kindred Ventures, said, “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 require a unique training strategy and learning loop approach with a deep understanding of each language and market.

Ken Asada, Partner / Sho Yamanaka, Principal, Salesforce Ventures, said, “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, said, “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.”

About Kotoba Technologies

Founded in 2023 by Noriyuki Kojima and Jungo Kasai (CTO), Kotoba Technologies builds advanced real time speech AI models for East Asia. The company develops Koto, a proprietary voice AI model designed for text to speech, speech to text, and real time speech to speech translation with sub-50ms latency across Japanese, Korean and Chinese.

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