Rein Security raises $25 million to monitor corporate AI agents whilst they are in action

The Israeli start-up, founded in 2024, places a ‘sidecar’ in the client’s cloud to monitor and block its agents’ actions in real time. It has now raised a total of 35 million.

Rein Security has announced a $25 million Series A round, co-led by Glilot Capital and Sienna Venture Capital, with participation from Corner Ventures, Atlacle and RNP Capital Advisors. Founded in 2024 by Matan Bar-Efrat and Netanel Rubin, the company brings its total funding to $35 million. It has 31 employees spread between Tel Aviv and New York.

Control the agent at runtime

The product is based on a "sidecar" technology that runs next to AI agents and observes, as they run, the code they launch and the resources they access. Rules make it possible to block behavior deemed dangerous in real time. Rein also says it secures the AI supply chain without passing data through a gateway. According to Netanel Rubin, the difference with the competition is that the platform is installed in the customer's cloud environment and primarily targets agents developed in-house.

Since the commercial launch in January 2026, the company claims to have increased its turnover by eight and its number of customers by five, and now protects thousands of agents totalling millions of shares.