Best Open Source Security Tools

Compare and discover the best Open Source Security software and tools for your team. Find the right solution for your needs.

3 vendors

Elastic

SIEM

6 products

Elastic Security provides an open-source SIEM platform built on the Elastic Stack (Elasticsearch, Logstash, Kibana, Beats) for collecting, indexing, and analyzing security logs from endpoints, networks, clouds (AWS, Azure, Google Cloud), and firewalls. It supports ECS-compliant index mappings, threat detection via KQL queries for brute force and lateral movement, correlation rules for multi-stage attacks, IOC matching with enrich policies, and Watcher-based alerting. Best for SOC teams needing scalable search analytics, real-time monitoring, and integration with EDR, XDR, SOAR in resource-constrained environments.

Centralized security event collectionAutomatic data source onboardingPrebuilt and custom detection rules+6

Greenbone Enterprise Appliance

Vulnerability Management

1 product

Greenbone Enterprise Appliance (also known as OpenVAS, Open Vulnerability Assessment System, Greenbone's open-source scanner) provides professional vulnerability management built on the OpenVAS framework. It offers robust scanning, asset management, and reporting capabilities, with both an enterprise appliance for organizations seeking reliable, scalable security assessments and an open-source edition often used for cost-effective vulnerability assessment, penetration testing support, and educational purposes.

Network vulnerability scanning applianceSeverity-based vulnerability prioritizationRemediation recommendation reporting+7

ProjectDiscovery (Nuclei)

Attack Surface Management

1 product

ProjectDiscovery (Nuclei) is an open-source, template-driven vulnerability scanning engine that is used in attack surface management to discover exposed assets, identify internet-facing services, and detect weaknesses across web applications, APIs, DNS, cloud infrastructure, and networks. In the ASM scope, it is strongest as a scanner and validation layer rather than a broad asset inventory platform, giving security teams attacker-style visibility into exposed hosts and services. It is a fit for practitioners who want programmable, repeatable scanning with a large community template ecosystem and minimal vendor lock-in. ProjectDiscovery also offers adjacent SaaS and agentic products, but Nuclei itself remains the core scanning engine.

Continuously monitor exposed assetsScan with community templatesDetect exposed services and panels+7

What is Open Source Security software?

Compare and discover the best Open Source Security software and tools for your team. Find the right solution for your needs. With 3 open source security tools listed on Picari, you can compare features, pricing models, and real user experiences side-by-side, without speaking to a single sales rep until you're ready.

Who needs open source security tools?

Open Source Security software is typically adopted by teams that have outgrown manual processes and need repeatable, scalable workflows. You'll get the most value if:

Your team spends more than 5 hours/week on tasks that could be automated
You're scaling past 10 team members and need consistent processes
You need better visibility into performance metrics and ROI
Your current tools don't integrate well with the rest of your stack

Buying criteria checklist for open source security

Before committing to a open source security platform, run through this evaluation checklist:

Does it integrate with your CRM and existing stack?

What's the total cost of ownership (setup + seats + add-ons)?

How steep is the learning curve for your team?

Does it scale with your expected growth over 12–24 months?

What does onboarding and customer support look like?

Can you trial it with real data before committing?

Common mistakes when evaluating open source security tools

1.Buying based on demos alone. A polished demo doesn't reveal how the tool handles your actual data and workflows. Always run a proof-of-concept.
2.Ignoring total cost of ownership. The sticker price is rarely the full cost, factor in implementation, training, integrations, and potential add-on fees.
3.Not involving end users in the evaluation. The people who'll use the tool daily should have a say. Top-down purchases often lead to low adoption.
4.Comparing too many tools at once. Shortlist 2–3 finalists max. Evaluating 5+ tools in parallel leads to decision fatigue and delayed timelines.

How to evaluate open source security tools on Picari

Picari is built to help security teams evaluate cybersecurity tools on their terms, no cold calls, no spam, no pressure. Here's how to get started:

Browse and compare, Review features, pricing, and team fit for each tool above.
Start a Briefing, Describe your problem and get a personalised shortlist of vendors in minutes.
Run a Stack Audit, See how a new tool fits alongside what you already use, and identify gaps or overlaps.
Open an Evaluation Room, Collaborate with your team, organize requirements, and message vendors directly, all in one place.

Not sure which open source security tool fits?

Start a Briefing to tell us what you're trying to solve, get a shortlist and a stack audit in minutes.

Top Open Source Security tools on Picari (2026)

Here are some of the most popular open source security tools currently listed on the platform:

Elastic Security, freemium pricing · Elastic Security provides an open-source SIEM platform built on the Elastic Stac…
Greenbone Enterprise Appliance, $$$ pricing · Greenbone Enterprise Appliance (also known as OpenVAS, Open Vulnerability Assess…
ProjectDiscovery (Nuclei), Free pricing · ProjectDiscovery (Nuclei) is an open-source, template-driven vulnerability scann…