Together AI raises $800M at $8.3B valuation as enterprises ditch closed models for open-source — TFN

Together AI raised $800 million at an $8.3 billion valuation, with Aramco Ventures leading the round.

The startup claims customers can cut inference costs by up to 60 times compared with closed-model rivals.

Annual bookings have topped $1.15 billion as enterprises shift toward open-source AI.

Together AI has raised an $800 million in Series C funding led by Aramco Ventures, valuing the company at $8.3 billion, up from $3.3 billion in February 2025. Vista Equity Partners, General Catalyst, Emergence Capital, Nvidia, March Capital, Pegatron, and S Ventures also joined the round.

The San Francisco-based company has never built a proprietary foundation model. Instead, it built the cloud infrastructure that lets enterprises run other companies’ open-source models cheaply and at scale, a bet that has pushed its annual bookings past $1.15 billion.