Open Source Alternatives to Microsoft 365 Defender
20 open source Cybersecurity options similar to Microsoft 365 Defender, ranked by named competitors first, sector overlap, and our 0-100 AI-readiness score. Every company listed publishes its source: each one carries an open source sector tag and a public GitHub repository.
0sec11CybersecurityAn applied cybersecurity research lab using AI agents to autonomously discover, exploit, and verify software vulnerabilities.
Open source · Self-hostable
Socket64Software Supply Chain SecuritySan Francisco, United States$60.0MSocket is a software supply chain security company that proactively blocks malicious open-source packages and extensions in AI-driven software development.
Open source
Backslash Security56CybersecurityTel Aviv, Israel$27.0MAgentic endpoint security for AI coding, providing visibility, governance, and real-time protection.
Open source
Slauth.io43EnterpriseAshburn, United States$1.5MArk Infotech offers Cybersecurity, AI/ML, Data Analytics, and IT consulting services, including the Slauth.io IAM Policy Copilot.
Open source · Self-hostable
Falco10CybersecurityOpen-source, cloud-native runtime security tool for detecting anomalous application behavior across hosts, containers, and Kubernetes.
Open source · Self-hostable
- Puck52Endpoint SecurityUnited States
Open-source, AI-driven endpoint investigation tool for security teams.
Open source · Self-hostable
ORY47Identity & Access ManagementBerlin, Germany$17.0MOpen-source identity and authorization services for applications, offering composable and scalable IAM solutions.
Open source · Self-hostable
Umbrasec9CybersecurityIndependent defensive security research focused on detection engineering, threat analysis, and open-source tooling for defenders.
Open source
Kryptvakt8CybersecurityKryptvakt offers a secure, decentralized platform for managing and sharing sensitive data.
Open source
Zsvirt2Open SourceA production-ready, lightweight open-source virtualization platform for environments from homelabs to hyperscale infrastructure.
Open source
Snyk76AI Coding AssistantBoston, United States$488.5MSnyk is a developer security platform that helps software teams find and fix vulnerabilities in code, open source dependencies, containers, and cloud infrastructure.
Open source · Self-hostable
Chainguard62CybersecuritySeattle, United States$385.0MSecures the software supply chain with verifiable builds and open-source security tooling.
Open source · Self-hostable
Bitwarden57CybersecuritySanta Barbara, United States$100.0MOpen-source password manager for individuals, teams, and businesses.
Open source · Self-hostable
ARMO56EnterpriseTel Aviv, Israel$34.5MARMO provides an open-source Kubernetes security platform, Kubescape, for end-to-end security from development to production.
Open source · Self-hostable
Fleet Device Management55CybersecuritySan Francisco, USA$32.0MAutonomous endpoint management platform to counter AI-accelerated exploits.
Open source · Self-hostable
OWASP38CybersecurityRaleigh, USAA global non-profit foundation dedicated to improving software security through open community collaboration.
Open source · Self-hostable
Outshift19Agentic AICisco's internal incubation engine for emerging technologies like agentic AI and quantum networking.
Open source · Self-hostable
Openthreatgrid8CybersecurityOpen honeynet telemetry, responsible threat intelligence sharing, and reproducible security research workflows for defenders and researchers.
Open source
Gako7CybersecurityOpen-source, self-hostable secret manager where the server cannot read your secrets.
Open source · Self-hostable
Logz.io63EnterpriseTel Aviv, Israel$122.0MLogz.io provides an observability platform for cloud-native businesses, combining open-source tools for monitoring and security.
Open source · Self-hostable