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Cybersecurity · head to head

OWASP ZAP vs Tenable Nessus

OWASP ZAP logo

OWASP ZAP

Cybersecurity

Free, open-source web application scanner and intercepting proxy, now governed by the Software Security Project.

From
Free
Rated
-
Full reviewWebsite
Tenable Nessus logo

Tenable Nessus

Cybersecurity

Network vulnerability scanner

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: OWASP ZAP authenticated scanning of modern single-page applications is the hard part and ZAP makes you build it by hand: session handling, token refresh and login scripts are configured per application, and a misconfigured session means the scanner logs itself out and reports a clean result for pages it never reached.; Tenable Nessus nessus Professional is $4,790 for one year, sold as an annual licence rather than a per scan or usage based fee
  • They diverge on capability: OWASP ZAP covers Intercepting proxy, Tenable Nessus covers Network scanning.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which OWASP ZAP and Tenable Nessus actually diverge.

Attributes where OWASP ZAP and Tenable Nessus differ
AttributeOWASP ZAPTenable Nessus
Pricing modelfreesubscription
PlatformsDesktop, Cli, ApiWindows, Linux, Macos, Cloud
Founded20012002

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Cybersecurity).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in OWASP ZAP

  • Intercepting proxy
  • Passive scanner
  • Active scanner
  • AJAX spider
  • Automation Framework
  • Headless daemon and REST API
  • Docker images
  • Add-on marketplace

Only in Tenable Nessus

  • Network scanning
  • Vulnerability detection
  • Configuration assessment
  • Malware detection
  • Compliance checking
  • Cloud security assessment
  • Mobile scanning
  • API access

What people use each for

The jobs each tool is most often brought in to do.

OWASP ZAP

  • Adding a baseline security scan to every application's pipeline where per-target commercial licensing would limit coverage to a handfulnot Tenable Nessus
  • Manual penetration testing that needs an intercepting proxy, request replay and fuzzing without a paid licence per testernot Tenable Nessus
  • Teaching developers what an attack against their own endpoint looks like, using a tool they can install themselvesnot Tenable Nessus
  • Pre-release regression scanning of an internal application that would never justify a commercial DAST subscriptionnot Tenable Nessus

Tenable Nessus

  • Vulnerability scanning of servers, network devices and web applicationsnot OWASP ZAP
  • Configuration and compliance auditing against hardening benchmarksnot OWASP ZAP
  • Point in time assessments by consultants and penetration testersnot OWASP ZAP

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

OWASP ZAP

  • Authenticated scanning of modern single-page applications is the hard part and ZAP makes you build it by hand: session handling, token refresh and login scripts are configured per application, and a misconfigured session means the scanner logs itself out and reports a clean result for pages it never reached.
  • There is no support contract in the product, so when a scan breaks the day before a release the escalation path is a GitHub issue and a community chat, which is not an answer that satisfies a delivery manager or an auditor who wants a named responsible party.
  • Active scanning sends genuine attack traffic, so it can create records, trigger emails, exhaust rate limits or destabilise a fragile environment, and pointing it at production without prior agreement produces an incident rather than a test result.
  • Output needs triage: passive rules generate large volumes of low-severity informational findings about headers and cookie flags that bury the few results that matter, and a team without someone tuning the rule set stops reading the report within a few sprints.
  • As a dynamic scanner it can only test what it can reach, so authorisation flaws between accounts, business logic abuse and anything behind an undiscovered endpoint go unreported, and a passing ZAP scan is evidence of nothing more than the absence of the classes of bug it looks for.

Tenable Nessus

  • Nessus Professional is $4,790 for one year, sold as an annual licence rather than a per scan or usage based fee
  • Support beyond the base entitlement costs an extra $400 per year for Advanced Support with 24x365 phone and chat access
  • The on demand training course is a separate $275 purchase for a single person for one year
  • Multi year discounts require paying for two or three years up front

Pricing, plan by plan

OWASP ZAP

Free
  • Free & Open SourceFree
    • Full functionality
    • Active & passive scanning
    • Spider

Tenable Nessus

Free
  • Nessus EssentialsFree
    • Up to 16 ips
    • Network scanning
    • Vulnerability assessment
  • Nessus Professional$2600/year
    • Unlimited targets
    • Enterprise features
    • Advanced analytics
  • Nessus Expert$5200/year
    • All Professional features
    • Cloud integration
    • Advanced reporting

Which should you pick?

Choose OWASP ZAP if

  • You need intercepting proxy.
  • You want to start without paying.
  • You work on Desktop, Cli, Api.
  • You also want passive scanner.
OWASP ZAP review

Choose Tenable Nessus if

  • You need network scanning.
  • You want to start without paying.
  • You work on Windows, Linux, Macos, Cloud.
  • You also want vulnerability detection.
Tenable Nessus review

Questions people ask

Is OWASP ZAP or Tenable Nessus better?
Neither clearly leads. OWASP ZAP starts at Free and Tenable Nessus at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, OWASP ZAP or Tenable Nessus?
OWASP ZAP starts at Free and Tenable Nessus at Free.
Does OWASP ZAP or Tenable Nessus run on more platforms?
OWASP ZAP runs on Desktop, Cli, Api. Tenable Nessus runs on Windows, Linux, Macos, Cloud.
Can I use OWASP ZAP for free?
Both have a free tier, so you can try either at no cost before committing.
What is OWASP ZAP best used for?
OWASP ZAP is most often used for adding a baseline security scan to every application's pipeline where per-target commercial licensing would limit coverage to a handful, manual penetration testing that needs an intercepting proxy, request replay and fuzzing without a paid licence per tester, teaching developers what an attack against their own endpoint looks like, using a tool they can install themselves, pre-release regression scanning of an internal application that would never justify a commercial dast subscription. Of those, adding a baseline security scan to every application's pipeline where per-target commercial licensing would limit coverage to a handful and manual penetration testing that needs an intercepting proxy, request replay and fuzzing without a paid licence per tester are not what Tenable Nessus is typically brought in for.
What can OWASP ZAP do that Tenable Nessus cannot?
OWASP ZAP covers Intercepting proxy, Passive scanner, Active scanner, AJAX spider. Tenable Nessus covers Network scanning, Vulnerability detection, Configuration assessment, Malware detection.

Answered from the vendors’ own pages

OWASP ZAP: Is it still called OWASP ZAP?

The project left OWASP in August 2024 and is now governed by the Software Security Project, with core development sponsored by Checkmarx. The tool is now just ZAP, though most existing documentation, courses and search results still use the OWASP name.

Tenable Nessus: What are the three Nessus offerings?

Nessus Essentials is a free introductory offering for educators, students, and career starters, limited to 16 IPs for scanning. Nessus Professional is designed for consultants and SMBs, providing unlimited IT scans across any location. Nessus Expert is the premium offering extending Professional with web application scanning, infrastructure-as-code scanning, and external attack surface assessment up to 5 domains.

Source
OWASP ZAP: Is it free for commercial use?

Yes. It is Apache 2.0 licensed, with no per-application, per-scan or per-user cost, and it can be used and modified commercially without a licence agreement.

Tenable Nessus: What OS platforms does Nessus support?

Nessus runs on Debian/Kali Linux, Fedora, FreeBSD, Mac OS X, Red Hat/CentOS, SUSE Linux, Ubuntu, and various Windows versions including Server 2008, 2012, and Windows 7-10.

Source
OWASP ZAP: Can it replace a penetration test?

No. It automates checks for known vulnerability classes against endpoints it can reach. It does not reason about business logic, chain findings into an attack, or test authorisation between accounts, which is most of what a tester actually does.

Tenable Nessus: Can I use Nessus to scan third-party networks as a consultant?

Yes, Tenable permits you to use Nessus to scan third-party networks. Nessus Professional is ideal for consultants.

Source
OWASP ZAP: Does it run in CI?

Yes, through the official Docker images and the Automation Framework, which defines scan jobs in YAML so configuration lives in the repository. A baseline passive scan is the usual starting point because it is fast and non-intrusive.

Tenable Nessus: Can Nessus perform PCI external scanning?

Yes, you can use Nessus Professional to perform external network scans as required by the PCI DSS 11.2.2 requirement.

Source
OWASP ZAP: How does it compare to Burp Suite?

Burp Suite Professional is the more polished manual testing tool and has a stronger scanner and extension ecosystem, but it is licensed per tester and Burp Suite Enterprise per target. ZAP is the better fit where cost per target is the binding constraint; many teams use both.

Tenable Nessus: What additional features does Nessus Expert provide?

Web application scanning, which is dynamic application security testing (DAST) providing comprehensive visibility and insight into web application security issues; scanning code repositories for vulnerabilities; and assessing external attack surface with subdomain discovery.

Source
Tenable Nessus: What support options exist for Nessus Professional?

Standard Support includes software upgrades, patches, plugin access, and 24x7 support via chat and community portal. Advanced Support adds 24x7 phone access and committed SLAs: P1 less than 2 hours, P2 less than 4 hours, P3 less than 12 hours, P4 less than 24 hours.

Source
Tenable Nessus: How frequently are Nessus plugins updated?

Nessus plugins are updated daily, based on when vendors and security research sites publish new vulnerabilities.

Source
Tenable Nessus: How does licensing work in virtual machine environments?

Whether you are using Nessus in a physical or a virtual environment, the IP addresses or hosts that you are scanning from must be licensed.

Source
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