Together AI, a developer of infrastructure for companies running open-source AI models, has secured $800 million in Series C financing at an $8.3 billion post-money valuation. Aramco Ventures led the round, marking one of the largest funding events for an AI infrastructure platform this year.
The San Francisco-based startup provides a cloud layer that lets enterprises train, fine-tune, and deploy open-source models without managing the underlying GPU clusters. Together AI has become a key player in the open-source AI stack, competing with companies like Fireworks AI and Anyscale as enterprises increasingly seek alternatives to proprietary API providers.
The round was part of a banner week for big-ticket funding. Energy startup Joulent secured $1.75 billion, compliance platform LeapXpert raised $180 million, and 8090 Solutions, co-founded by Chamath Palihapitiya, picked up $135 million. Global startup investment hit a record $510 billion in the first half of 2026, with 60% of capital flowing into rounds of $1 billion or more.
