Inworld, the AI research lab and inference provider, announced on October 1, 2026 that it has acquired Ultravox, the platform developers use to build real-time voice agents. Financial terms were not disclosed. As an immediate benefit, all built-in Inworld voices on Ultravox now run Realtime TTS-2, the top-ranked TTS model on the Artificial Analysis leaderboard, at no additional cost and with no code changes.
On October 1, 2026, Inworld announced it has acquired Ultravox, the platform developers use to build real-time voice agents. Ultravox team members have joined Inworld and will continue developing the platform. The companies had already worked together through a text-to-speech partnership, and Inworld says the acquisition accelerates its speech-to-speech research and voice agent capabilities.
Inworld frames the deal as two halves of the same conversation coming together. Ultravox brings speech understanding, reasoning, task completion, and tools for managing turn-taking and interruptions in live voice conversations; Inworld contributes its top-of-benchmarks speech models — Realtime TTS-2 and Realtime STT-1 — plus model serving and real-time inference infrastructure for consumer-facing AI applications. The first customer benefit shipped immediately: all built-in Inworld voices on Ultravox now run Realtime TTS-2, the top-ranked text-to-speech model on the Artificial Analysis leaderboard, which supports 200+ languages, sub-100ms latency, and natural-language steering that lets developers control pacing, tone, and emotional delivery through inline instructions.
Existing Ultravox customers keep running as usual: there is no migration or code change required, existing voice IDs continue to work, the TTS-2 upgrade comes at no additional cost, and agents using third-party voices such as ElevenLabs or Cartesia remain unchanged for now. Inworld CEO Kylan Gibbs said, 'Ultravox has built a platform that developers rely on for real-time voice agents... Bringing Realtime TTS-2 to the Inworld voices customers already use is the first benefit we're delivering.' Zach Koch, co-founder and former CEO of Ultravox, said Inworld 'moves fast and shares our commitment to delivering real-time AI at scale' and called it 'the right home for Ultravox.'
The acquisition continues a consolidation wave in voice agent infrastructure, as model providers absorb the tooling layers around them. Inworld says the deal advances its work on speech-to-speech experiences that bring speech understanding, reasoning, and expressive voice generation closer together, with further capabilities and improvements for Ultravox customers promised 'in the coming weeks.' Equal AI, a customer already using Inworld's voice technology before the deal, called bringing the voices and platform 'under one roof' a 'natural next step' for the voice experiences it builds.
