Rein Security has officially emerged from stealth with a bold mission: close the most dangerous blind spot in modern application security—what actually happens inside production environments. Founded by industry veterans Matan Bar Efrat and Netanel Rubin and backed by Glilot Capital, Rein introduces a patent-pending platform that delivers real-time context and protection directly within running applications.
As organizations race to adopt APIs, AI-generated code, and emerging architectures like Model Context Protocols (MCP), security teams struggle to understand how their software behaves once it reaches production. Rein Security addresses this gap with a production-first approach that replaces assumptions with verified runtime insight.
Enterprises such as Lemonade and HiBob already rely on Rein to protect business-critical applications in live environments, signaling strong early confidence in the company’s vision and technology.
The AppSec Problem: Visibility Ends Before Production
For years, application security has focused on scanning code before deployment. Static and dynamic testing tools flag potential vulnerabilities, but they rarely explain how applications behave in the real world. Security teams often chase theoretical risks that never materialize, while attackers exploit weaknesses that pre-production tools never detect.
Rein’s own research underscores this challenge. In a recent survey, more than three-quarters of CISOs, AppSec leaders, and developers ranked production-level visibility as their top requirement for improving application security. They want to see live execution paths, real API usage, and actual data flows—not just predictions.
The explosion of APIs, microservices, and AI-driven applications has made the problem even more urgent. Each new component introduces complexity and expands the attack surface. Traditional AppSec tools struggle to keep pace with this dynamic environment.
Rein Security positions itself as a new category of solution: a platform grounded entirely in real production insight.
A Platform Built on Runtime Reality
Rein’s technology creates a continuous, real-time stream of application behavior inside production environments. The platform correlates requests, responses, APIs, libraries, and lines of code to build granular baselines of what “normal” looks like for each application.
When something deviates, security teams see it immediately and with full context. Instead of guessing whether a vulnerability matters, they can confirm whether attackers can actually reach it.
Matan Bar Efrat, co-founder and CEO of Rein Security, explains the company’s philosophy clearly:
“Security teams have been forced to play guesswork for far too long. 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 in production, teams resolve real issues quickly instead of wasting time on endless investigations.”
This production-first approach shifts AppSec from a theoretical discipline to an operational one.
Key Capabilities of the Rein Platform
Rein Security delivers a set of capabilities designed for modern software environments:
Complete production visibility
Rein provides a real-time, code-level view of application behavior. Teams can observe how APIs interact, which libraries execute, and how requests flow through the system.
Runtime protection
The platform enables granular, impact-centric protection against both zero-day and known (one-day) vulnerabilities. Security teams can block real exploitation attempts instead of reacting to generic alerts.
AI and MCP security
Rein supports visibility and protection for AI agents, AI-native applications, and Model Context Protocols. As organizations adopt AI-driven architectures, Rein helps them understand how these components behave in production.
Agentless architecture
The system applies production context with less than one millisecond of performance impact. It avoids proxies, sampling, and eBPF, which often introduce operational complexity and blind spots.
Cross-domain AppSec support
Rein integrates production context across API security, Software Composition Analysis (SCA), SAST, DAST, and AI security. This unified view allows teams to prioritize risks that truly matter.
Together, these capabilities create a new axis for application security—one that runs continuously in production instead of stopping at deployment.
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Solving Real-World AppSec Use Cases
Rein’s platform directly addresses critical AppSec challenges such as API security and SCA reachability.
Most organizations struggle to understand which APIs and libraries actually run in production. Rein applies runtime context to identify what exists in live environments and how attackers might exploit it. This insight allows teams to distinguish between theoretical vulnerabilities and validated risks.
For example, instead of flagging every vulnerable library version, Rein shows whether the vulnerable code path executes in production and whether external requests can reach it. This clarity helps teams focus remediation efforts where they matter most.
The result: fewer false positives, faster response times, and stronger alignment between security and development teams.
Customer Confidence from Day One
Early customers highlight the value of Rein’s real-time visibility. Jonathan Jaffe, CISO at Lemonade, emphasizes the importance of understanding what actually happens inside applications.
“Uptime and security are strict requirements,” Jaffe said. “We need a way to understand what’s really happening in our apps without relying on limited data or guesses. Rein provides granular baselines and real production visibility, so when something deviates, it’s real—not another false signal.”
This confidence allows Lemonade to detect and stop exploitation attempts, support developers with actionable insight, and protect production environments without disruption.
Such testimonials demonstrate Rein’s ability to translate advanced technology into practical business outcomes.
Industry Perspective: A New Way to Think About Risk
Analysts also see Rein’s approach as a shift in how organizations manage application risk. Alexei Balaganski, Lead Analyst at KuppingerCole Analysts, describes production visibility as a fundamentally different perspective.
“Modern application environments have become more dynamic and difficult to reason about using traditional AppSec models,” Balaganski said. “Improving visibility into real execution context helps security teams prioritize risk, reduce friction, and adapt security practices to modern software development.”
This shift aligns with broader industry trends toward runtime security, observability, and context-driven decision-making.
Built by Veterans, Backed for Growth
Rein Security benefits from leadership with deep experience in security and software engineering. Founders Matan Bar Efrat and Netanel Rubin built the company after years of frustration with incomplete data and slow investigations in traditional AppSec programs.
The company operates from Tel Aviv and New York City and counts Glilot Capital among its investors. Rein launched in 2024 and already serves Fortune 500 organizations across financial and business-critical industries.
This combination of technical vision, customer validation, and financial backing positions Rein for rapid growth as application environments continue to evolve.
The Future of Application Security Runs in Production
Rein Security’s emergence from stealth marks a turning point in how organizations approach application security. Instead of relying on pre-production snapshots, Rein brings security directly into live environments where real threats occur.
By delivering continuous visibility, runtime protection, and AI-aware security, Rein enables teams to move from reactive defense to informed, proactive control. The platform helps CISOs and AppSec leaders answer the most important question: what risks actually matter right now?
As APIs, AI, and interconnected systems define the next generation of software, Rein Security aims to ensure that protection keeps pace with innovation—without slowing it down.
For more information or to request a demo, visit www.reinsec.io or https://reinsec.io/book-a-demo.