Together AI raises 800 million dollars in Series C as open-source cloud demand surges

Together AI has raised 800 million dollars in a Series C round led by Aramco Ventures, valuing the company at more than eight billion dollars. The round also drew Vista Equity Partners, General Catalyst, Emergence Capital, Nvidia, March Capital, Pegatron, and SentinelOne’s S Ventures. Together AI says it now generates more than one billion dollars in annual bookings and that usage of open-source models on its platform has tripled over the past year, according to data it cites from OpenRouter.

The valuation represents a sharp jump. Together AI raised 305 million dollars in a Series B in February 2025 at a valuation of roughly three billion dollars, led by General Catalyst and Prosperity7, the venture arm of Aramco. Before that, it closed a 102 million dollar Series A in November 2023 from Kleiner Perkins, and The Information reported in March that the company was in talks to raise one billion dollars at a valuation near seven and a half billion dollars.

Together AI operates as a cloud platform for running open-source AI models, positioning itself between the hyperscalers and the developers who want alternatives to closed systems from OpenAI or Anthropic. Its customers include Cursor, the AI coding tool, Cognition, the maker of the Devin AI software engineer, and Decagon, an AI customer support startup. The company says it will use the new capital to expand its compute infrastructure and accelerate development of its inference engine.

The founding team lends the company academic credibility. Co-founder and CEO Vipul Ved Prakash previously built Topsy, the social analytics company Apple acquired in 2013 for more than 200 million dollars. Co-founders Percy Liang, a Stanford computer science professor, and Ce Zhang, who has held positions at ETH Zurich and the University of Chicago, bring deep research ties to the company, which was founded in 2022.

The raise lands in a market pouring capital into AI infrastructure at an unprecedented pace, with neocloud valuations soaring as demand for GPU compute continues to outstrip supply. Upscale AI closed a 190 million dollar extension in June, bringing its total funding to 500 million dollars at a two billion dollar valuation. TensorWave, which builds its cloud on AMD chips rather than Nvidia’s, raised 350 million dollars in a Series B at a valuation near one and a half billion dollars.

Together AI’s open-source bet sets it apart from the neocloud pack. While rivals like Groq and RunPod focus primarily on renting out raw GPU capacity, Together AI bundles compute with its own inference optimisation software, which it says can cut the cost of running popular models by up to 80 percent. That software layer is the moat the company is building around what would otherwise be a commodity hardware business.

Aramco Ventures leading the round signals growing Middle Eastern interest in the infrastructure underpinning artificial intelligence, rather than just the models themselves. The question for Together AI is whether its open-source positioning and software edge can hold as the hyperscalers, flush with hundreds of billions in capital spending, build out their own inference capabilities at a scale no startup can match.