Cartesia

Cartesia is an AI voice infrastructure company founded in 2023 and headquartered in San Francisco, California. The company was co-founded by Bharat Vasan and a team of researchers focused on building low-latency speech synthesis models for production applications.

Cartesia's primary product is Sonic, a streaming text-to-speech API designed for real-time use cases such as AI voice agents, interactive applications, and conversational interfaces. Sonic-3, the company's latest model, supports over 40 languages and includes expressive capabilities such as laughter and emotional range. The API is built around low-latency streaming, targeting developers who need sub-100ms response times for voice-enabled products.

Cartesia raised a $31 million Series A round, with participation from investors including Andreessen Horowitz. The company operates with a small team and competes in the text-to-speech API market alongside providers such as ElevenLabs and OpenAI's voice offerings. Its GitHub organization hosts open-source tooling related to its speech models.