Baseten closes $1.5B Series F at $13B valuation, led by Altimeter

Baseten, the San Francisco-based AI inference platform, closed a $1.5 billion Series F led by Altimeter Capital, Conviction, and Spark Capital—its fourth raise in 18 months and the latest mega-deal in AI infrastructure. The financing values the company at $13 billion (across two tranches at $13B and $11B) and reflects surging demand for inference at the application layer as open-source and closed-source models converge in cost and capability.

Baseten's growth has been extraordinary: revenue has grown 20x year-over-year, the platform now processes over 1 billion inference requests daily across 87 global clusters spanning 18 cloud providers, and leading AI application companies like Cursor, Lovable, Harvey, and OpenEvidence now direct 30–50% of model spending toward custom and post-trained models rather than frontier APIs alone.

The capital will fund headcount expansion (the company is tripling staff this year), compute infrastructure, and enterprise go-to-market. Architects building multi-model stacks where proprietary post-trained inference is the differentiator are watching Baseten as the standard infrastructure play for that workload shift.