Rein Security, a trusted application security company for leading enterprises, has emerged from stealth to tackle what it describes as critical blind spots in application and AI security.
The firm said it is building on an initial $8m seed round led by Glilot Capital.
Rein’s platform is designed to provide real-time context and protection inside application production environments, aiming to help security teams understand how software behaves once it is live, rather than relying on pre-production testing alone.
The company says its technology delivers a continuous view of code behaviour, requests and risks inside production, which it believes can help organisations validate whether issues are real and prioritise remediation more effectively. Rein added that enterprises in financial and other business-critical services are among those that rely on its approach, naming Lemonade and HiBob as customers.
The company is positioning itself against an AppSec landscape it says is being reshaped by the growth of APIs, AI-generated code and applications, and model context protocols (MCP).
Rein said the business was founded by security leaders Matan Bar Efrat and Netanel Rubin after what it described as years of teams being forced to make decisions with incomplete data and time-consuming investigations. In a survey referenced by the company, Rein said more than three-quarters of CISOs, AppSec leaders and developers ranked production-level visibility into applications as their top requirement for improving AppSec.
The platform’s stated capabilities include “complete visibility in production”, “runtime protection”, “AI-security”, an “agentless architecture” that it says operates with under one millisecond of performance impact, and support across multiple AppSec domains including API Security, SCA, SAST, DAST and AI security.
Rein Security CEO Matan Bar Efrat said, “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.
“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.”
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