Signal Together AI raises $800M at $8.3B valuation for open-source AI infrastructure

Summary

Together AI, founded in 2022, raised $800 million in a Series C round led by Aramco Ventures — with participation from Vista Equity Partners, General Catalyst, Emergence Capital, Nvidia, Salesforce Ventures, March Capital, Pegatron and SentinelOne's S Ventures — more than doubling its valuation to $8.3 billion from $3.3 billion in a February 2025 round. The platform lets companies train and run AI workloads on open models including DeepSeek, MiniMax and Kimi at a claimed cost reduction of up to 60 times versus closed-model rivals. The company's annual bookings have topped $1.15 billion, and it now serves more than one million developers and thousands of enterprise customers including Cursor and Cognition. Together AI separately secured commitments for more than 500 megawatts of compute capacity as it expands from training into inference services. CEO Vipul Ved Prakash said "The future of AI won't be owned by a few companies. It will be built by millions of developers and businesses, and open-source models are making that possible."