Sail Research Raises $80 Million to Build Infrastructure for Long-Horizon AI Agents

Sail Research has raised 80 million dollars in Seed and Series A funding at a 450 million dollar valuation, announced in a press release. The Series A round was led by Kleiner Perkins, while the Seed round was led by Sequoia Capital. Other investors included Redpoint Ventures, Theory Ventures, Vine Ventures, CRV, A*, and Abstract Ventures, along with angel investors such as John Hennessy of Alphabet, Lip-Bu Tan of Intel, and Tri Dao of Together AI.

Sail Research builds infrastructure designed for AI agents that work autonomously on complex tasks over extended periods. Its platform includes two main components: an inference stack optimized for throughput and efficiency, and Sailboxes, a sandbox environment that runs for hours or days and charges only for active compute time. The company states that its system enables large scale agent workloads that are not limited by traditional rate or cost constraints.

According to the company, its inference stack achieves higher efficiency through deep customization of open source inference engines and intelligent workload distribution. In a benchmark test, Sail’s system reached 90.72 percent accuracy in the BrowseComp-Plus evaluation while operating at up to ten times lower cost than competing platforms.

Sail’s infrastructure is already used by companies such as Parallel Web Systems, Jack and Jill, and Detail.dev. The platform is compatible with OpenAI-based workflows and supports several open source models including DeepSeek, Gemma, GLM, Kimi, and Nemotron.