Seattle voice AI startup Ultravox, which launched as Fixie, has been acquired by Inworld for an undisclosed sum.
Ultravox was founded in 2022 by Google and Apple veterans to build a speech model for real-time, natural-sounding AI voice agents.
In perhaps its most whimsical project, the startup launched the HiSanta.ai website in December 2023, allowing users to chat with Santa Claus, who spoke with a British accent, as well as Rudolph, Mrs. Claus and other North Pole notables. The site is no longer active.
The company announced a $17 million seed round in March 2023, and PitchBook put its valuation at $51.46 million at the time. Redpoint Ventures led the round, which included Madrona Venture Group, Zetta Venture Partners, SignalFire, Bloomberg Beta and Kearny Jackson. Current and former executives at Google, Amazon and Apple also invested.
Ultravox has 10 employees, according to LinkedIn. It was unclear whether the entire team would join Inworld, which is based in Mountain View, Calif.
“We’re excited to welcome members of the Ultravox team and continue building the platform,” said Inworld CEO Kylan Gibbs in a statement.
The acquisition will allow Inworld to adopt Ultravox’s technology for managing turn-taking and interruptions in voice conversations with AI, which should improve performance in real-time chats.
Inworld has raised $119.8 million since launching in 2021 and is valued at $515 million, according to PitchBook.
Ultravox co-founder Zach Koch was most recently the company’s CEO. His LinkedIn profile says he is now vice president of product at Shopify. Peter Salas, who joined the company as a software engineer in 2023, is currently listed as chief technology officer.
The startup’s original CEO, Matt Welsh, departed two years ago and is now head of AI systems at defense company Palantir Technologies. Co-founders Hessam Bagherinezhad and Justin Uberti also left, in 2023 and 2024 respectively, and both joined OpenAI.
The release announcing the acquisition said Ultravox customers would be upgraded to Inworld’s Realtime TTS-2 voice technology.
