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Cybersecurity · head to head

Fortinet FortiGate vs Tenable Nessus

Fortinet FortiGate logo

Fortinet FortiGate

Cybersecurity

Next-generation firewall with AI-powered threat protection

From
$500/year
Rated
-
Full reviewWebsite
Tenable Nessus logo

Tenable Nessus

Cybersecurity

Network vulnerability scanner

From
Free
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: Fortinet FortiGate security services are sold as separate FortiGuard subscription bundles, so ATP, UTP and ENT determine which protections are actually active; 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: Fortinet FortiGate covers Next-generation firewall, Tenable Nessus covers Network scanning.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Fortinet FortiGate and Tenable Nessus actually diverge.

Attributes where Fortinet FortiGate and Tenable Nessus differ
AttributeFortinet FortiGateTenable Nessus
Starting price$500/yearFree
Free tierNoYes
PlatformsHardware, Virtual, CloudWindows, Linux, Macos, Cloud
Founded20002002

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 Fortinet FortiGate

  • Next-generation firewall
  • Intrusion prevention
  • SSL/TLS inspection
  • Application control
  • Web filtering
  • SD-WAN
  • Zero-trust network access
  • AI-powered threat detection

Only in Tenable Nessus

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

Both cover

  • AWS
  • Azure
  • Google Cloud
  • Cloud deployment

What people use each for

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

Fortinet FortiGate

  • Next-generation firewalling at data centre, campus and branch scalenot Tenable Nessus
  • Secure SD-WAN across distributed sitesnot Tenable Nessus
  • Zero trust network access to internal applicationsnot Tenable Nessus
  • Virtual firewalls in AWS, Azure, Google Cloud and Oraclenot Tenable Nessus
  • Ruggedised deployments in industrial environmentsnot Tenable Nessus

Tenable Nessus

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

Where each one falls short

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

Fortinet FortiGate

  • Security services are sold as separate FortiGuard subscription bundles, so ATP, UTP and ENT determine which protections are actually active
  • Throughput is tied to the appliance model, from 500 Mbps on the FortiGate 30G to 520 Gbps on the 7121F, so capacity planning is a hardware purchase
  • Pricing is not published and goes through partners

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

Fortinet FortiGate

$500/year
  • FortiGate Entry$500/year
    • Basic firewall
    • VPN support
    • Threat protection
  • FortiGate Enterprise$2500/year
    • Advanced threat protection
    • SSL inspection
    • Application control
  • FortiGate Ultimate$10000/year
    • All Enterprise features
    • Zero-trust access
    • AI-powered analytics

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 Fortinet FortiGate if

  • You need next-generation firewall.
  • You work on Hardware, Virtual, Cloud.
  • You also want intrusion prevention.
Fortinet FortiGate 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 Fortinet FortiGate or Tenable Nessus better?
Neither clearly leads. Fortinet FortiGate starts at $500/year and Tenable Nessus at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Fortinet FortiGate or Tenable Nessus?
Tenable Nessus has a free tier; the other does not. Paid plans start at $500/year for Fortinet FortiGate and Free for Tenable Nessus.
Does Fortinet FortiGate or Tenable Nessus run on more platforms?
Fortinet FortiGate runs on Hardware, Virtual, Cloud. Tenable Nessus runs on Windows, Linux, Macos, Cloud.
Can I use Tenable Nessus for free?
Yes. Tenable Nessus has a free tier, so you can try it without paying. Fortinet FortiGate starts at $500/year.
What is Fortinet FortiGate best used for?
Fortinet FortiGate is most often used for next-generation firewalling at data centre, campus and branch scale, secure sd-wan across distributed sites, zero trust network access to internal applications, virtual firewalls in aws, azure, google cloud and oracle. Of those, next-generation firewalling at data centre, campus and branch scale and secure sd-wan across distributed sites are not what Tenable Nessus is typically brought in for.
What can Fortinet FortiGate do that Tenable Nessus cannot?
Fortinet FortiGate covers Next-generation firewall, Intrusion prevention, SSL/TLS inspection, Application control. Tenable Nessus covers Network scanning, Vulnerability detection, Configuration assessment, Malware detection. Both handle AWS, Azure, Google Cloud, Cloud deployment.

Answered from the vendors’ own pages

Fortinet FortiGate: What are the FortiGate security bundle options?

Fortinet offers three FortiGuard AI-Powered Security Services bundles: ENT Bundle (ultimate security for networks, web, file, SaaS, data, and devices), UTP Bundle (advanced web and network protection), and ATP Bundle (protection against network intrusions and malware with IPS, antivirus, and application control).

Source
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.

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Fortinet FortiGate: How do I get pricing for FortiGate?

Pricing is not published on the product page. To obtain a quote, you can request a free product demo or connect with a security expert through the contact options on the site.

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.

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Fortinet FortiGate: Is there a free trial for FortiGate?

The product page does not mention a free trial. However, Fortinet offers a free product demo that allows you to evaluate the solution before committing to a purchase.

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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.

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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.

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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.

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Tenable Nessus: How frequently are Nessus plugins updated?

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

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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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