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Cybersecurity · head to head

Tenable Nessus vs Zscaler Internet Access

Tenable Nessus logo

Tenable Nessus

Cybersecurity

Network vulnerability scanner

From
Free
Rated
-
Full reviewWebsite
Zscaler Internet Access logo

Zscaler Internet Access

Cybersecurity

Secure cloud-native internet and SaaS access

From
$100/year
Rated
-
Full reviewWebsite

The short version

  • Only Tenable Nessus has a free tier, so it costs nothing to try first.
  • Each has a real cost: Tenable Nessus nessus Professional is $4,790 for one year, sold as an annual licence rather than a per scan or usage based fee; Zscaler Internet Access the pricing page names two base tiers, Essentials Platform and Zscaler Platform, plus modular add ons including three Digital Experience Monitoring tiers, but publishes no dollar figures anywhere and routes buyers to a demo request for cost
  • They diverge on capability: Tenable Nessus covers Network scanning, Zscaler Internet Access covers Secure web gateway.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Tenable Nessus and Zscaler Internet Access actually diverge.

Attributes where Tenable Nessus and Zscaler Internet Access differ
AttributeTenable NessusZscaler Internet Access
Starting priceFree$100/year
Free tierYesNo
PlatformsWindows, Linux, Macos, CloudWeb, Desktop, Mobile
Founded20022007

Identical on both: pricing model (subscription), 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 Tenable Nessus

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

Only in Zscaler Internet Access

  • Secure web gateway
  • Cloud firewall
  • URL filtering
  • Advanced threat protection
  • Data loss prevention
  • Cloud sandbox
  • Browser isolation
  • CASB

Both cover

  • Splunk
  • ServiceNow
  • SOC2 Type 2
  • ISO 27001
  • GDPR
  • Cloud deployment

What people use each for

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

Tenable Nessus

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

Zscaler Internet Access

  • Cloud Securitynot Tenable Nessus
  • Zero Trustnot Tenable Nessus
  • Web Securitynot Tenable Nessus

Where each one falls short

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

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

Zscaler Internet Access

  • The pricing page names two base tiers, Essentials Platform and Zscaler Platform, plus modular add ons including three Digital Experience Monitoring tiers, but publishes no dollar figures anywhere and routes buyers to a demo request for cost

Pricing, plan by plan

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

Zscaler Internet Access

$100/year
  • ZIA Business$100/year
    • Web security
    • URL filtering
    • Cloud firewall
  • ZIA Transformation$200/year
    • All Business features
    • Advanced threat protection
    • Cloud sandbox
  • ZIA Unlimited$350/year
    • All Transformation features
    • Cloud browser isolation
    • CASB

Which should you pick?

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

Choose Zscaler Internet Access if

  • You need secure web gateway.
  • You work on Web, Desktop, Mobile.
  • You also want cloud firewall.
Zscaler Internet Access review

Questions people ask

Is Tenable Nessus or Zscaler Internet Access better?
Neither clearly leads. Tenable Nessus starts at Free and Zscaler Internet Access at $100/year, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Tenable Nessus or Zscaler Internet Access?
Tenable Nessus has a free tier; the other does not. Paid plans start at Free for Tenable Nessus and $100/year for Zscaler Internet Access.
Does Tenable Nessus or Zscaler Internet Access run on more platforms?
Tenable Nessus runs on Windows, Linux, Macos, Cloud. Zscaler Internet Access runs on Web, Desktop, Mobile.
Can I use Tenable Nessus for free?
Yes. Tenable Nessus has a free tier, so you can try it without paying. Zscaler Internet Access starts at $100/year.
What is Tenable Nessus best used for?
Tenable Nessus is most often used for vulnerability scanning of servers, network devices and web applications, configuration and compliance auditing against hardening benchmarks, point in time assessments by consultants and penetration testers. Of those, vulnerability scanning of servers, network devices and web applications and configuration and compliance auditing against hardening benchmarks are not what Zscaler Internet Access is typically brought in for.
What can Tenable Nessus do that Zscaler Internet Access cannot?
Tenable Nessus covers Network scanning, Vulnerability detection, Configuration assessment, Malware detection. Zscaler Internet Access covers Secure web gateway, Cloud firewall, URL filtering, Advanced threat protection. Both handle Splunk, ServiceNow, SOC2 Type 2, ISO 27001.

Answered from the vendors’ own pages

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
Zscaler Internet Access: How many pricing tiers does Zscaler Internet Access offer?

Zscaler Internet Access offers two main platform bundles: the Essentials Platform (entry-level) and the Zscaler Platform (comprehensive). Specific pricing is not published online.

Source
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
Zscaler Internet Access: Are there optional add-on modules available?

Yes. Zscaler offers extensive optional capabilities in five categories including Inline Cyberthreat Protection, Private Access enhancements, Data Security, Security Operations, and Zero Trust Branch.

Source
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
Zscaler Internet Access: How is Zscaler Zero Trust Branch priced?

Zero Trust Branch is sized by encrypted throughput (200 Mbps to 10 Gbps) or endpoint count (200 to 5,000 endpoints), with pricing varying by configuration.

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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
Zscaler Internet Access: How do I get Zscaler pricing?

Zscaler does not publish pricing online. You must request a demo or contact their sales team to receive a pricing quote.

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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.

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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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