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Cybersecurity · head to head

Tenable Nessus vs Unit21

Tenable Nessus logo

Tenable Nessus

Cybersecurity

Network vulnerability scanner

From
Free
Rated
-
Full reviewWebsite
Unit21 logo

Unit21

Cybersecurity

No-code fraud and AML risk operations platform for fintechs and neobanks

From
On request
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; Unit21 it is built for fintech scale rather than card issuer scale, so organisations reaching very high transaction volumes generally re-evaluate against heavier platforms and face a migration.
  • They diverge on capability: Tenable Nessus covers Network scanning, Unit21 covers No-code rule builder.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Tenable Nessus and Unit21 actually diverge.

Attributes where Tenable Nessus and Unit21 differ
AttributeTenable NessusUnit21
Starting priceFreeOn request
Pricing modelsubscriptionquote
Free tierYesNo
PlatformsWindows, Linux, Macos, CloudWeb
Founded2002Unknown

Identical on both: 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 Unit21

  • No-code rule builder
  • Case management
  • SAR filing
  • Backtesting
  • Identity and device signals
  • Data ingestion API

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 Unit21
  • Configuration and compliance auditing against hardening benchmarksnot Unit21
  • Point in time assessments by consultants and penetration testersnot Unit21

Unit21

  • A neobank whose sponsor bank requires a documented monitoring programme before it will keep the BIN sponsorshipnot Tenable Nessus
  • A crypto exchange needing SAR filing and case management without building an internal compliance engineering teamnot Tenable Nessus
  • A payments startup where the fraud lead needs to ship a new rule the same day a new attack pattern appearsnot Tenable Nessus
  • A lender consolidating fraud alerts from three point tools into one investigator queue with a single audit trailnot 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

Unit21

  • It is built for fintech scale rather than card issuer scale, so organisations reaching very high transaction volumes generally re-evaluate against heavier platforms and face a migration.
  • No-code rule authoring shifts power to the risk team, which is the point, but without governance it produces rule sprawl that nobody can explain to an examiner two years later.
  • Detection quality depends on the signals you feed it, so a thin integration produces thin results and the platform cannot compensate with proprietary consortium data the way larger vendors do.
  • Pricing is quoted by volume with an annual commitment, so a fintech whose growth stalls pays for headroom it did not use.
  • SAR filing coverage is oriented to United States FinCEN reporting, so firms filing in the United Kingdom, European Union or Asia handle those submissions outside the tool.

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

Unit21

On request
  • Unit21 Platform$undefined/year
    • Priced by monitored volume and modules, annual contract
    • Fraud, AML and case management packaged separately
    • Implementation and historical data backfill quoted with the subscription

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 Unit21 if

  • You need no-code rule builder.
  • You also want case management.
Unit21 review

Questions people ask

Is Tenable Nessus or Unit21 better?
Neither clearly leads. Tenable Nessus starts at Free and Unit21 at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Tenable Nessus or Unit21?
Tenable Nessus has a free tier; the other does not. Paid plans start at Free for Tenable Nessus and On request for Unit21.
Does Tenable Nessus or Unit21 run on more platforms?
Tenable Nessus runs on Windows, Linux, Macos, Cloud. Unit21 runs on Web.
Can I use Tenable Nessus for free?
Yes. Tenable Nessus has a free tier, so you can try it without paying. Unit21 starts at On request.
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 Unit21 is typically brought in for.
What can Tenable Nessus do that Unit21 cannot?
Tenable Nessus covers Network scanning, Vulnerability detection, Configuration assessment, Malware detection. Unit21 covers No-code rule builder, Case management, SAR filing, Backtesting.

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
Unit21: Do we need engineers to run it?

Only for the initial data integration. After that the design intent is that risk and compliance staff author and deploy rules themselves.

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
Unit21: Does it file SARs?

Yes, it generates and electronically files suspicious activity reports to FinCEN. Non-US regimes are not covered to the same depth.

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
Unit21: Can we test a rule before it goes live?

Yes. Backtesting against historical data to see projected alert volume is one of the more useful parts of the product, because alert volume is the real cost.

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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