Sail Research raises $80 million to build infrastructure for long-horizon AI agents; targets agent framework and compute orchestration.

Sail Research has raised $80 million in Seed and Series A funding at a $450 million valuation. The Series A round was led by Kleiner Perkins, with the Seed round led by Sequoia. Additional investors included Redpoint Ventures, Theory Ventures, Vine Ventures, CRV, A*, and Abstract Ventures. Angel investors included John Hennessy, chairman of Alphabet; Lip-Bu Tan, CEO of Intel; and Tri Dao, Chief Scientist at Together AI.

The company is building infrastructure purpose-built for the next generation of AI agents capable of working autonomously on complex tasks over hours or days. Today's infrastructure was largely designed for short, prompt-based interactions rather than long-running agent workloads, leaving agents constrained by compute, context, rate limits, and cost ceilings across platforms not designed for long-horizon use.

Sail's platform comprises two core components. First is an inference stack rebuilt around throughput and efficiency for agents that may spend billions of tokens on a single task. Second is Sailboxes, a sandbox environment that runs for hours or days while charging only for time agents are actively working. The company attributes its efficiency advantage to proprietary infrastructure optimizations, deep customization of open-source inference engines, intelligent workload distribution across providers, and use of underutilized compute.

In a recent benchmark, Sail's inference topped BrowseComp-Plus, achieving 90.72% accuracy at up to 10 times lower cost than leading alternatives. The platform is already powering AI-driven workflows at Parallel Web Systems, Jack and Jill, and Detail.dev. The API is compatible with existing OpenAI-based workflows and supports leading open-source models including DeepSeek, Gemma, GLM, Kimi, and Nemotron.

Sail Research was co-founded by CEO Neil Movva and CTO Samir Menon. Movva previously worked at NVIDIA, Apple, and Together AI, while Menon previously built large-scale systems at Apple.

CEO Neil Movva said: "Sail exists to make intelligence abundant. Every decision we make, from the chip level to the API, is about giving teams the tokens, the scale, and the runtime to build agents without limits."

CTO Samir Menon said: "Most inference infrastructure was designed to minimize latency on a single request, but that's the wrong optimization for agents, which need to sustain throughput across thousands of concurrent calls over hours. We've rebuilt the stack around that constraint, and the efficiency gains compound across every layer."

Aditya Naganath, Partner at Kleiner Perkins, said: "The infrastructure layer for the agent era is one of the most important bets in AI right now, and Neil and Samir are exactly the founders to build it. They bring a rare combination of deep compute expertise and systems rigor that only comes from having built at the limits of scale. Together, they're building the defining inference platform for long-horizon agents."

A Sail customer said: "Building on Sail lets us ship long-horizon agents with great economics. Trillions of tokens and counting, we're happy customers."