Together AI Raises $800M Series C at $8.3B Valuation to Scale Open Source Inference
Together AI has closed an $800 million Series C at an $8.3 billion post-money valuation, led by Aramco Ventures with participation from Vista Equity Partners, General Catalyst, Emergence Capital, NVIDIA, March Capital, Pegatron, and S Ventures (SentinelOne), among others. The round is one of the largest yet for a company positioned squarely in the open source AI infrastructure layer, and it lands at a moment when the economics of running AI at scale have become a defining concern for anyone building on top of frontier models.
The Core Bet: Open Models Are Cheaper, and Now Good Enough
Together AI’s pitch is built around a specific pain point: closed frontier-model pricing can consume a company’s entire margin. The company positions itself as the infrastructure layer for the alternative, helping customers train and run workloads on open models such as DeepSeek, Nemotron, MiniMax, and Kimi at a fraction of closed-model cost, while claiming comparable or better performance. Customers cited in the announcement report cost savings ranging from 6x to 60x versus closed-model pricing, with AI agent company Decagon specifically cutting inference costs sixfold after migrating to Together.
That value proposition appears to be translating into real usage. Together AI says its annual bookings crossed $1.15 billion last quarter, and that open source model usage across the industry has tripled over the past twelve months. The company now counts thousands of paying customers, including Cursor, Cognition, and Decagon — all names with substantial inference volume of their own. McKinsey research cited in the release adds a demand-side data point: nearly three-quarters of organizations expect to increase their use of open source AI going forward.
What the Capital Is For
The company plans to use the funding to expand its product and feature set as it pushes to become a leading inference provider, while scaling its compute capacity and infrastructure footprint. Notably, Together AI is projecting its infrastructure footprint will grow roughly 50-fold over the next five years — a figure that signals the company expects open source inference demand to keep compounding well beyond current levels, not merely track it.
Strategic Investor Signal
The investor lineup is worth reading closely. Aramco Ventures leading the round, alongside Schneider Electric’s SE Ventures, points to a growing convergence between AI infrastructure and energy infrastructure — Schneider Electric’s CEO Olivier Blum explicitly framed the investment around efficiency being the connective tissue between the two, arguing that more cost-effective AI translates into less energy consumed per workload. NVIDIA’s participation is also notable given Together AI’s inference-and-training focus sits directly on top of NVIDIA’s hardware stack, reinforcing the platform’s position in the broader AI compute supply chain rather than competing against it.
The Broader Thesis
Together AI CEO Vipul Ved Prakash has framed the company’s mission around treating intelligence as an increasingly foundational economic resource — comparable to electricity or bandwidth — with the underlying bet that open ecosystems, not a handful of closed labs, will ultimately win the largest share of that build-out. Founded in 2022, Together AI now says it powers over a million developers. Whether the open source cost advantage persists as closed-model providers respond on pricing will be the thing to watch, but for now Together AI’s bookings growth and enterprise customer base suggest the open source inference thesis has real commercial traction behind it, not just directional sentiment.