Nessus Alternatives 2026: 6 Free Options
Nessus alternatives: Greenbone (OpenVAS), Nuclei, Wazuh, Nmap and 2 more. Prices and licenses checked October 25, 2026.
•3 min read•Security Software & Testing
Verdict:Nessus Essentials is free for non-commercial use but limited to 5 IPs, with Essentials Plus at $199 a year for 20 IPs, and Nessus Professional is $4,790 for a one-year license. Consultants and companies cannot use Essentials, so the jump to Professional is steep, which is why people look elsewhere. The closest free replacement is Greenbone's OpenVAS, an open-source scanner with scheduled scans, reports and no IP cap, though the free edition lacks some enterprise-software coverage and support. Test its setup and reporting on a small network first. Wazuh takes a different approach: agents on each machine report vulnerabilities and configuration issues continuously, which suits a fleet you control. Nuclei, Nmap and ZAP are narrower tools that pair well together. Nmap finds what is exposed, Nuclei checks it for known issues and ZAP tests the web application, but you assemble the workflow and produce the report yourself. Trivy fits when your concern is container images and dependencies. What you lose is Nessus's plugin quality, credentialed scanning that is simple to set up, and compliance audit templates, so test the replacement against a host where you already know the findings. If a client or auditor expects Nessus reports specifically, keep a Professional license for that engagement and use the free tools for everything else.
Quick comparison
| Tool | Price | Platforms | Best for | Tested |
|---|---|---|---|---|
| Greenbone (OpenVAS) | Free (OPENVAS FREE is free of charge; it lacks enterprise-grade software coverage, automatic scan initialization, alerts, API access and support) | Linux, Docker | A free scanner without an IP cap | Docs only |
| Nuclei | Free (Free open-source template-based scanner) | macOS, Windows, Linux | Template-based checks in pipelines | Docs only |
| Wazuh | Free (free, no license cost; paid support and cloud not priced on the page) | Windows, Linux, macOS, Self-hosted | Continuous host monitoring with agents | Docs only |
| Nmap | Free (Free to download and use; embedding in proprietary products needs a separate OEM license) | macOS, Windows, Linux | Network discovery and port scanning | Docs only |
| ZAP | Free (Free and open source) | macOS, Windows, Linux | Testing a web application | Docs only |
| Trivy | Free (Free open-source scanner for containers, Kubernetes, code repositories, secrets and SBOMs) | macOS, Windows, Linux | Container images and infrastructure as code | Docs only |
| Rapid7 | Paid from $1.62 per asset/month, InsightVM, starting at 500 assets | Web browser | Vulnerability Management | Docs only |
Independent comparison. Paid placements are labelled separately; editorial links earn no affiliate commissions. Learn more.
Good fit if
- You need a free scanner with no IP limit (Greenbone (OpenVAS) is the pick)
- You want to scan from CI pipelines (Nuclei is the pick)
- You want continuous monitoring of a server fleet (Wazuh is the pick)
- You are testing a web application (ZAP is the pick)
- You want to find what is open on a network first (Nmap is the pick)
Not ideal if
- You rely on Nessus features or integrations that these tools do not replicate
Nessus today: Free (Nessus Essentials: free for non-commercial use, up to 5 IPs); paid from $4790 per year (Nessus Professional, 1-year license) (Nessus pricing, checked 2026-10-22).
Why people look for Nessus alternatives
Nessus Essentials is limited to 5 IPs and strictly non-commercial use. It excludes compliance checks, reporting, data export, Live Results and technical support, and plugin updates arrive on a 30-day delay. Commercial scanning means Nessus Professional at $4,790 for one year (Expert is $6,790), with Advanced Support a $400 add-on and training from $275.
Greenbone (OpenVAS)
Compared with Nessus: Greenbone's OPENVAS FREE is the closest free scanner: GPL-2.0 scanner, AGPL-3.0 manager and web interface. Unlike Nessus Essentials it has no 5-IP cap or non-commercial rule, but it lacks enterprise-software coverage and support that paid editions include.
Price: Free (OPENVAS FREE is free of charge; it lacks enterprise-grade software coverage, automatic scan initialization, alerts, API access and support) (Greenbone (OpenVAS) pricing, checked 2026-10-22).
Platforms and license: Linux, Docker. GPL-2.0 (openvas-scanner); AGPL-3.0 (gvmd, GSA) (open source).
Project activity: 4.9k GitHub stars · latest release v23.52.6 (Oct 27, 2026) · last commit Oct 27, 2026
Best for: A free scanner without an IP cap.
Nuclei
Compared with Nessus: Nuclei is MIT-licensed and runs community templates against web apps, networks and cloud services. It is easy to run from CI, unlike a Nessus server, but it checks for specific known issues and does not do credentialed patch audits.
Price: Free (Free open-source template-based scanner) (Nuclei pricing, checked 2026-10-22).
Platforms and license: macOS, Windows, Linux. MIT (open source).
Project activity: 32.4k GitHub stars · latest release v3.11.1 (Aug 8, 2026) · last commit Oct 27, 2026
Best for: Template-based checks in pipelines.
Worth knowing: Template-driven scanning of web apps, networks and cloud; not an authenticated host-patch auditor.
Wazuh
Compared with Nessus: Wazuh is a free GPL-2.0 XDR and SIEM with host agents that also covers compliance monitoring. Nessus scans hosts from outside on a schedule; Wazuh watches them continuously from inside, but you must deploy and maintain its stack.
Price: Free (free, no license cost; paid support and cloud not priced on the page) (Wazuh pricing, checked 2026-10-22).
Platforms and license: Windows, Linux, macOS, Self-hosted. GPL-2.0 (most code); AGPL-3.0 (engine) (open source).
Project activity: 17.5k GitHub stars · latest release v4.14.9 (Oct 15, 2026) · last commit Oct 27, 2026
Best for: Continuous host monitoring with agents.
Worth knowing: XDR/SIEM with host agents; free cloud trial.
Nmap
Compared with Nessus: Nmap is free under its own NPSL license for discovery and port scans, and it supports NSE scripts for some vulnerability checks. It does not score or report findings like Nessus, so it complements a scanner rather than replacing one.
Price: Free (Free to download and use; embedding in proprietary products needs a separate OEM license) (Nmap pricing, checked 2026-10-22).
Platforms and license: macOS, Windows, Linux. Nmap Public Source License (NPSL).
Best for: Network discovery and port scanning.
Worth knowing: Port and service discovery with NSE scripts; not a full vulnerability management product.
ZAP
Compared with Nessus: ZAP is Apache-2.0, free, and made for web application testing. ZAP is not a general host and network scanner like Nessus, so it covers only the web application part of the job.
Price: Free (Free and open source) (ZAP pricing, checked 2026-10-22).
Platforms and license: macOS, Windows, Linux. Apache-2.0 (open source).
Project activity: 16k GitHub stars · latest release v2.17.0 (Dec 15, 2025) · last commit Oct 27, 2026
Best for: Testing a web application.
Worth knowing: Web application scanner; docker images also available.
Trivy
Compared with Nessus: Trivy is Apache-2.0 and scans container images, Kubernetes, repositories, secrets and SBOMs. If your Nessus use is mostly checking images and dependencies, it is a free fit; it will not audit a Windows server's patch level.
Price: Free (Free open-source scanner for containers, Kubernetes, code repositories, secrets and SBOMs) (Trivy pricing, checked 2026-10-22).
Platforms and license: macOS, Windows, Linux. Apache-2.0 (open source).
Project activity: 38.8k GitHub stars · latest release v0.76.1 (Oct 21, 2026) · last commit Oct 27, 2026
Best for: Container images and infrastructure as code.
Other popular options (paid)
Rapid7
Compared with Nessus: InsightVM is billed per asset, from $1.62 per asset per month starting at 500 assets, where Nessus Professional is $4,790 for a one-year license. The pricing page lists no free tier.
Price: Paid from $1.62 per asset/month, InsightVM, starting at 500 assets (Rapid7 pricing, checked 2026-10-25).
Which one to pick
- You need a free scanner with no IP limit: Greenbone (OpenVAS)
- You want to scan from CI pipelines: Nuclei
- You want continuous monitoring of a server fleet: Wazuh
- You are testing a web application: ZAP
- You want to find what is open on a network first: Nmap
Limits of this review
Docs-only for Greenbone (OpenVAS), Nuclei, Wazuh, Nmap, ZAP, Trivy: we did not install or run them, so feature claims come from vendor pages and we did not test import from Nessus. Vendor prices and free limits change; confirm on the linked pricing page before you buy or migrate.
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Kevin Fan
Kevin Fan is a SaaS founder. He runs Free Instead Of, which tracks free and open-source alternatives to paid software and checks each price and free-plan limit against the vendor's own pages.
Methodology
Based on official pricing and product pages checked between 2026-10-22 and 2026-10-25: Nessus, Greenbone (OpenVAS), Nuclei, Wazuh, Nmap, ZAP, Trivy, Rapid7. Prices, free limits and licenses are the figures shown on those pages on those dates. No tool on this page was installed or run. No accounts were created.