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Cybersecurity · head to head

Clerk vs Tenable Nessus

Clerk logo

Clerk

Cybersecurity

Drop-in user authentication and management for developers

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: Clerk pricing scales with monthly retained users, which can grow expensive quickly for consumer apps with large user bases.; 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: Clerk covers Prebuilt UI components, Tenable Nessus covers Network scanning.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

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

Attributes where Clerk and Tenable Nessus differ
AttributeClerkTenable Nessus
Pricing modelfreemiumsubscription
Platformsweb, ios, android, apiWindows, Linux, Macos, Cloud
FoundedUnknown2002

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 Clerk

  • Prebuilt UI components
  • Organization management
  • Multi-factor authentication
  • Social sign-on
  • Billing
  • Enterprise connections

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.

Clerk

  • Adding sign-in and user profiles to a web or mobile app quicklynot Tenable Nessus
  • B2B SaaS apps needing organizations and role-based accessnot Tenable Nessus
  • Startups wanting prebuilt UI instead of building auth in-housenot Tenable Nessus
  • Apps needing MFA and fraud detection out of the boxnot Tenable Nessus

Tenable Nessus

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

Where each one falls short

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

Clerk

  • Pricing scales with monthly retained users, which can grow expensive quickly for consumer apps with large user bases.
  • Enterprise SSO connections beyond the first are billed as add-ons, adding cost for larger organizations.
  • The Business tier's extra dashboard seats cost $20/month each, which adds up for larger teams.
  • Enterprise-tier features like the 99.99% uptime SLA require annual contracts rather than flexible monthly billing.

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

Clerk

Free
  • HobbyFree
    • 50,000 MRU limit per app
    • Up to 3 dashboard seats
    • Unlimited applications
  • Pro$25/month
    • 50,000 MRUs included, $0.02/MRU overage
    • Up to 3 dashboard seats
    • 1 Enterprise Connection included
  • Business$300/month
    • 50,000 MRUs included with volume pricing
    • 10 dashboard seats included
    • SOC2 report and priority support
  • Enterprise$undefined/month
    • Custom pricing, annual billing
    • 99.99% uptime SLA
    • HIPAA available, dedicated Slack channel

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 Clerk if

  • You need prebuilt ui components.
  • You want to start without paying.
  • You work on web, ios, android, api.
  • You also want organization management.
Clerk 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 Clerk or Tenable Nessus better?
Neither clearly leads. Clerk 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, Clerk or Tenable Nessus?
Clerk starts at Free and Tenable Nessus at Free.
Does Clerk or Tenable Nessus run on more platforms?
Clerk runs on web, ios, android, api. Tenable Nessus runs on Windows, Linux, Macos, Cloud.
Can I use Clerk for free?
Both have a free tier, so you can try either at no cost before committing.
What is Clerk best used for?
Clerk is most often used for adding sign-in and user profiles to a web or mobile app quickly, b2b saas apps needing organizations and role-based access, startups wanting prebuilt ui instead of building auth in-house, apps needing mfa and fraud detection out of the box. Of those, adding sign-in and user profiles to a web or mobile app quickly and b2b saas apps needing organizations and role-based access are not what Tenable Nessus is typically brought in for.
What can Clerk do that Tenable Nessus cannot?
Clerk covers Prebuilt UI components, Organization management, Multi-factor authentication, Social sign-on. Tenable Nessus covers Network scanning, Vulnerability detection, Configuration assessment, Malware detection.

Answered from the vendors’ own pages

Clerk: What does Clerk cost?

Clerk's Hobby plan is free with a 50,000 MRU limit; Pro is $25/month ($20/month billed annually), Business is $300/month ($250 annually), and Enterprise uses custom annual pricing.

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
Clerk: Is there a free plan and what are its limits?

Yes, the Hobby plan is free with a 50,000 monthly retained user (MRU) limit per app, up to 3 dashboard seats, and unlimited applications, with no credit card required.

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
Clerk: How is usage metered?

Clerk meters by monthly retained users (MRUs) — users who return to the app at least a day after signing up — with overage billed at $0.02 per MRU beyond the included 50,000 on paid plans.

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
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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