Radiant Security vs Legion Security

Radiant Security

Radiant Security is an AI SOC platform that triages and investigates security alerts across sources including endpoint, identity, cloud, email, network, and SIEM, then escalates what it assesses as real threats to analysts with documented reasoning. The vendor states analysts can execute response actions from within the platform, and an integrated log management option stores data in the customer's own S3 bucket. It deploys as cloud-hosted SaaS and connects to existing tools through API-based integrations, which press coverage of its Series A described as deployable in minutes.

Pros
  • Press coverage of the Series A reported API-based deployment in minutes, with a customer escalating a real threat within two hours of installation (SiliconANGLE)
  • Vendor states every AI conclusion includes transparent reasoning and a full audit trail
  • Raised a $15M Series A led by Next47 with participation from Lightspeed, Acrew, and others in November 2023 (SiliconANGLE, SecurityWeek)

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Legion Security

Legion Security helps enterprise security teams scale detection, investigation and response using agentic AI. The platform captures and learns from the real workflows analysts already use, and turns those actions into agentic playbooks the team can trust. The vendor positions this as a way to adopt frontier AI models gradually while keeping operational trust, reducing manual effort and preparing for autonomous security capabilities. It deploys through the analyst's browser rather than through API integrations, and uses vision models combined with other methods to observe how analysts investigate alerts, so the enterprise can either codify those processes or optimise them into visual agentic workflows that the team can inspect. Legion Security has offices in New York and Tel Aviv and is backed by Coatue, Accel and Picture, with investors from Island, CrowdStrike, Wiz and Google DeepMind. The company was founded in 2024 by former Microsoft Sentinel team members and emerged from stealth in July 2025.

Pros
  • Raised $38M total: an $8M seed led by Picture Capital and Accel, and a $30M Series A led by Coatue (Calcalist, Fortune)
  • Founding team includes former members of Microsoft's Sentinel product, per Calcalist
  • Browser-based deployment is designed to avoid custom API integration work, per the company
  • Customers cited on the vendor site report outcomes such as an 81% reduction in MTTI/R (WELL Health Technologies, vendor-cited)

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