Rein Security, an AppSec firm focused on protecting production environments and addressing blind spots in app and AI security, has emerged from stealth with a platform launch and an $8m seed round.
The company is building on an initial $8m seed round, led by Glilot Capital. Rein says its technology is designed to give security teams a clearer view of how software behaves once deployed, as organisations grapple with the growth of APIs, AI-generated code and new application architectures, including model context protocols (MCP). It argues many existing tools identify issues earlier in the development cycle but do not show what is actually happening in production, leaving security leaders to investigate incidents with limited data.
The firm says the new backing supports its approach of applying runtime context to validate risk in production, helping teams understand which APIs and libraries are present in live applications, determine whether vulnerabilities are reachable, and prioritise remediation more effectively. Rein also claims its approach avoids disruption by operating with minimal performance impact and without relying on proxies, sampling or eBPF.
Rein points to early enterprise adoption across business-critical services, naming Lemonade and HiBob among customers relying on it to protect production applications.
“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, co-founder and 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.”
“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.”
“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 security teams prioritize risk, reduce friction, and adapt security practices to modern software development.”
Copyright © 2026 RegTech Analyst
Copyright © 2018 RegTech Analyst
