Open-source Microsoft Sentinel alternatives

Wazuh is a free and open-source platform for threat prevention, detection and response. It protects workloads across on-premises, virtualized, containerized and cloud environments and combines XDR and SIEM functions in one product. The code is written mainly in C++.

The solution consists of an endpoint security agent installed on monitored systems and a management server that collects and analyzes the agents' data. It is integrated with the Wazuh Indexer, which offers a search engine and visualization for navigating security alerts. Agents scan for malware, rootkits and suspicious anomalies, read system and application logs, and monitor files for changes to content, permissions, ownership and attributes.

Rule-based analysis of collected logs, including data received from network devices through syslog, helps surface misconfigurations, policy violations and attempted or successful attacks. Repository topics also cover vulnerability detection, configuration assessment, incident response and compliance such as PCI DSS. The repository lists its license as 'Other', so review the license files for the exact terms.

Graylog is a log management server written in Java and described by its maintainers as free and open. It centralizes log data from many systems so teams can search, view and analyze events in one place instead of connecting to each machine individually.

The repository topics point to support for common log formats and transports, including GELF and syslog, along with Kafka and AMQP inputs. Topics also place the project in log analysis, log collection, secure logging and SIEM territory, which reflects its use for monitoring and security work. Specific features were not available when this entry was written, because the vendor website could not be read.

Security Onion is a no-cost, open Linux distribution built for threat hunting, security monitoring across an enterprise, and log management. It bundles a suite of tools designed to work together so defenders get visibility into both network and host activity from a single platform.

The Security Onion Console is a unified web interface for analyzing events and managing the deployment, with its own tools for alerting, dashboards, hunting, packet capture, detections and case management. Underneath it uses the Elastic Stack for search, Suricata for network intrusion detection, Elastic Fleet for host monitoring, Zeek for network metadata and other tools such as osquery and CyberChef. The installer and configuration are largely shell scripts.

The repository license appears as 'Other' on GitHub. Security Onion is deployed on your own hardware or virtual machines, either standalone or as a distributed grid. It suits security operations centers, incident responders and blue teams that want an integrated, open alternative to commercial monitoring platforms.

Tracecat is open-source software for automating security operations, used by teams and AI agents together. It aims to give security teams everything they need to build agents and automate cyber defense in one place, from alert handling to incident response, with unlimited agents, cases, lookup tables and workflows.

Its building blocks include agents and skills built from prompts, tools and MCP, case management for tracking and resolving incidents with agent help, workflows that execute deterministic logic with resilience on Temporal, tables for storing and querying structured data, and a Tracecat MCP that turns prompts into automations from Claude Code, Codex and similar tools. The stack is Python with FastAPI and a Next.js interface.

Tracecat is licensed under AGPL-3.0 and can be self-hosted, with a managed cloud also offered by the vendor. It suits security operations, detection engineering and incident response teams that want a programmable, AI-ready alternative to proprietary SOAR tools.