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Cybersecurity · head to head

KnowBe4 vs Tenable Nessus

KnowBe4 logo

KnowBe4

Cybersecurity

World's largest security awareness training platform

From
$1/month
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: KnowBe4 published prices assume a three year term, so the quoted per seat rate depends on a long commitment; 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: KnowBe4 covers Security awareness training, Tenable Nessus covers Network scanning.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which KnowBe4 and Tenable Nessus actually diverge.

Attributes where KnowBe4 and Tenable Nessus differ
AttributeKnowBe4Tenable Nessus
Starting price$1/monthFree
Free tierNoYes
PlatformsWeb, Mobile, EmailWindows, Linux, Macos, Cloud
Founded20102002

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 KnowBe4

  • Security awareness training
  • Phishing simulation
  • Risk assessments
  • Compliance training
  • Incident reporting
  • Custom policies
  • Behavior analytics
  • Microsoft 365

Only in Tenable Nessus

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

Both cover

  • API access
  • Splunk
  • SOC2 Type 2
  • ISO 27001
  • GDPR
  • Cloud deployment

What people use each for

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

KnowBe4

  • Security awareness training and simulated phishing for staffnot Tenable Nessus
  • Tracking employee susceptibility to phishing over timenot Tenable Nessus

Tenable Nessus

  • Vulnerability scanning of servers, network devices and web applicationsnot KnowBe4
  • Configuration and compliance auditing against hardening benchmarksnot KnowBe4
  • Point in time assessments by consultants and penetration testersnot KnowBe4

Where each one falls short

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

KnowBe4

  • Published prices assume a three year term, so the quoted per seat rate depends on a long commitment
  • Pricing is banded by seat count, and the lowest band of 25 to 50 seats pays the highest rate
  • Accounts above 1,000 seats have no published price and require a custom quote
  • Third party integrations, Compliance Plus and PhishER Plus are all separately priced per seat add ons
  • The Foundation tier carries 200 training modules against more than 1,000 on Advanced, so content volume is the main gate

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

KnowBe4

$1/month
  • Basic$1/month
    • Per user
    • Training modules
    • Phishing templates
  • Advanced$2/month
    • All Basic features
    • Advanced phishing
    • Risk assessments
  • Pro$3/month
    • All Advanced features
    • API access
    • Custom content

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 KnowBe4 if

  • You need security awareness training.
  • You work on Web, Mobile, Email.
  • You also want phishing simulation.
KnowBe4 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 KnowBe4 or Tenable Nessus better?
Neither clearly leads. KnowBe4 starts at $1/month and Tenable Nessus at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, KnowBe4 or Tenable Nessus?
Tenable Nessus has a free tier; the other does not. Paid plans start at $1/month for KnowBe4 and Free for Tenable Nessus.
Does KnowBe4 or Tenable Nessus run on more platforms?
KnowBe4 runs on Web, Mobile, Email. 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. KnowBe4 starts at $1/month.
What is KnowBe4 best used for?
KnowBe4 is most often used for security awareness training and simulated phishing for staff, tracking employee susceptibility to phishing over time. Of those, security awareness training and simulated phishing for staff and tracking employee susceptibility to phishing over time are not what Tenable Nessus is typically brought in for.
What can KnowBe4 do that Tenable Nessus cannot?
KnowBe4 covers Security awareness training, Phishing simulation, Risk assessments, Compliance training. Tenable Nessus covers Network scanning, Vulnerability detection, Configuration assessment, Malware detection. Both handle API access, Splunk, SOC2 Type 2, ISO 27001.

Answered from the vendors’ own pages

KnowBe4: What does KnowBe4 cost per employee?

KnowBe4 charges per seat per month on a subscription basis. For 51-100 employees, SAT Foundation costs $2.13/month per seat and SAT Advanced costs $3.40/month per seat. Prices decrease with larger employee counts.

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.

Source
KnowBe4: Does KnowBe4 offer a free trial?

KnowBe4 does not offer a full free version, but free tools are available separately including assessments and simulators.

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
KnowBe4: Are there add-on costs beyond the base plan?

Yes, optional add-ons include Third-Party Integrations ($1.10-$1.20/seat/month), Compliance Plus ($0.82-$0.93/seat/month), PhishER Plus ($1.15-$1.50/seat/month), and Student Edition ($0.17/seat/month).

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
KnowBe4: What currencies does KnowBe4 accept?

KnowBe4 accepts pricing in USD, AUD, BRL, CAD, EUR, GBP, SGD, and ZAR.

Source
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
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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