One of the biggest misconceptions in cybersecurity is that effective protection requires expensive commercial tools. While enterprise vendors would love you to believe that, the reality is that many open-source tools rival — and sometimes exceed — their commercial counterparts.
Here are five open-source security tools that we use daily with our SMB clients, and why they matter for your business.
1. Wazuh — Your Security Operations Centre in a Box
What it does: Wazuh is a unified SIEM (Security Information and Event Management) and XDR (Extended Detection and Response) platform. It collects logs from your endpoints, cloud services, and network devices, then analyses them for threats in real-time.
Why it matters: Without a SIEM, you're flying blind. You won't know if someone is brute-forcing your admin accounts, if malware is communicating with a command-and-control server, or if an employee's credentials have been compromised. Commercial SIEMs like Splunk or Microsoft Sentinel can cost thousands per month. Wazuh provides comparable functionality for the cost of the infrastructure to run it.
Best for: Any business that needs centralised security monitoring — which is every business.
2. n8n — Security Automation Without the Price Tag
What it does: n8n is a workflow automation platform (similar to Zapier or Microsoft Power Automate) that you self-host. In a security context, we use it to build automated alert triage, incident response workflows, and threat intelligence enrichment.
Why it matters: A SIEM that generates alerts nobody responds to is useless. n8n lets us build workflows that automatically enrich alerts with context, suppress known false positives, escalate genuine threats, and even take automated containment actions. Commercial SOAR (Security Orchestration, Automation and Response) platforms cost £50,000+ per year.
Best for: Businesses running Wazuh or any SIEM that need intelligent alert management.
3. Velociraptor — Digital Forensics Made Accessible
What it does: Velociraptor is an endpoint investigation and forensics tool. When you suspect a compromise, Velociraptor lets you quickly collect forensic artifacts, hunt for indicators of compromise across your fleet, and understand exactly what happened.
Why it matters: When a security incident occurs, the first question is always "what did they access?" Without forensic capability, you're guessing. Velociraptor gives you the ability to investigate incidents thoroughly, which is crucial for understanding impact, meeting disclosure requirements, and preventing recurrence.
Best for: Organisations that want incident investigation capability as part of their security monitoring stack.
4. Nuclei — Fast, Comprehensive Vulnerability Scanning
What it does: Nuclei is a template-based vulnerability scanner that can check your web applications, APIs, and network services for known vulnerabilities. Its community maintains thousands of detection templates that are updated constantly.
Why it matters: Regular vulnerability scanning is a fundamental security practice, and it's required by most compliance frameworks. Commercial scanners like Tenable or Qualys charge per-asset licensing fees that add up quickly. Nuclei provides fast, accurate scanning with a community-driven template library that often catches vulnerabilities faster than commercial alternatives.
Best for: Any business running web applications or APIs that needs regular vulnerability assessments.
5. GoPhish — Test Your Team Before Attackers Do
What it does: GoPhish is a phishing simulation platform that lets you send realistic (but safe) phishing emails to your team to measure susceptibility and improve awareness.
Why it matters: Phishing remains the number one attack vector for SMBs. Training alone isn't enough, but regular simulations combined with technical controls significantly reduce risk. Commercial phishing platforms charge £3-10 per user per month. GoPhish is free.
Best for: Any organisation that wants to measure and reduce phishing risk across their team.
The Catch: Tools Need Expertise
These tools are powerful, but they're not plug-and-play. They need proper deployment, configuration, tuning, and ongoing management. An unconfigured SIEM generates noise, not intelligence.
That's where we come in. Our Security Monitoring service deploys and manages these tools for you, giving you enterprise-grade security operations without needing to hire a security team. And because the tools are open-source, there's no vendor lock-in — you own your data and your infrastructure.