Rein Security launches to provide protection inside application production environments

Rein Security emerged from stealth to address blind spots in application and AI security. Building on an initial $8 million seed round led by Glilot Capital, Rein delivers a patent pending technology that provides real-time context and protection inside application production environments.

Enterprises across a variety of industries, such as financial and other business-critical services, rely on Rein to protect applications running in production, including Lemonade and HiBob.

The AppSec landscape is undergoing rapid change as organizations contend with the growth of APIs, AI-generated code and applications, as well as model context protocols (MCP). Yet most organizations still struggle to see how their applications behave in production. After years of being forced to make decisions with incomplete data and time-consuming investigations, security leaders Matan Bar Efrat and Netanel Rubin founded Rein to build a platform grounded entirely in real production insight.

“Security teams have been forced to play guesswork for far too long and we can no longer allow application security to be rooted in assumptions instead of reality,” said Matan Bar Efrat, CEO of Rein Security. “We founded Rein to give CISOs and AppSec leaders the ability to protect every app, MCP, library and API without disruption. By seeing and controlling exactly what happens to apps in production, teams can resolve real issues quickly rather than spending excessive time on investigations and analysis.”

AppSec production visibility with real-time insights

Most AppSec tools stop at code scanning and pre-production testing, which surfaces issues but fails to show how applications actually behave once they are in production. In a recent survey, Rein found that more than three-quarters of CISOs, AppSec leaders and developers identified gaining production-level visibility into their applications as their number one requirement for improving AppSec. Rein is creating a whole new axis that closes the gap by providing organizations with a direct, continuous livestream of code behavior, requests and risks inside production environments.

“Uptime and security are strict requirements,” said Jonathan Jaffe, CISO at Lemonade. “That’s why we need a way to understand what’s really happening in our apps, without relying on limited data, proxies or guesses. Rein provides exactly that. Its granular baselines and real production visibility give us confidence that when something deviates, it’s real – not another false signal. That way we can detect and stop actual exploitation attempts, understand what the application is actually doing, and support developers with the visibility they need, all without impacting production.”

The Rein platform solves key AppSec use cases, including API security and SCA reachability, by applying application runtime context to surface validated risks in production versus theoretical ones. This approach helps teams move beyond static assumptions to understand which APIs and libraries are present in applications in production, determine vulnerability reachability and focus remediation efforts more effectively.

Key capabilities of the Rein platform include:

• Complete visibility in production: A real-time, code-level view into application behavior.
• Runtime protection: Granular and impact-centric protection covering both zero-day and one-day exploits.
• AI-security: Visibility and protection needed to mitigate risks from MCP, AI agents, AI-native apps and emerging application architectures.
• Agentless architecture: Applies production context with under one millisecond of performance impact and no reliance on proxies, sampling or eBPF.
• Cross-domain application security support: Applies production context across multiple AppSec domains, including API Security, SCA, SAST, DAST and AI security.

“Modern application environments are becoming more dynamic, interconnected, and difficult to reason about using traditional AppSec models,” said Alexei Balaganski, Lead Analyst at KuppingerCole Analysts. “Improving visibility into real execution context in production introduces a different way of thinking about application risk. That perspective can help securi