Inworld today announced that it has acquired Ultravox, a platform developers use to build real-time voice agents. Ultravox team members who have joined Inworld will continue developing the platform.

The acquisition accelerates Inworld’s speech-to-speech research and voice agent capabilities. Ultravox brings expertise in areas such as turn-taking and interruption handling, helping developers build voice agents that can respond to users in real time.

“Ultravox has built a platform that developers rely on for real-time voice agents,” said Kylan Gibbs, CEO of Inworld. “We’re excited to welcome members of the Ultravox team and continue building the platform. Bringing Realtime TTS-2 to the Inworld voices customers already use is the first benefit we’re delivering.”

For Ultravox customers, all built-in Inworld voices are upgraded to Realtime TTS-2, the top ranked text-to-speech model on the Artificial Analysis leaderboard. The model supports 200+ languages, sub 100ms latency, and natural-language direction, allowing developers to control pacing, tone, and emotional delivery with inline instructions.

About Inworld

Inworld is an AI research lab and inference provider building the models and infrastructure behind some of the largest consumer-facing AI applications. They build first-party speech models, serve LLMs, and run the realtime inference behind modular APIs used by some of the largest consumer AI apps.

About Ultravox

Ultravox is a platform for building real-time voice agents, with capabilities for turn-taking, interruption handling, and voice delivery.

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Inworld’s acquisition of Ultravox brings voice AI and model inference under one roof, building the realtime infrastructure the next generation of consumer AI developers need.