Cybersecurity · head to head
Microsoft Defender vs Tenable Nessus
Microsoft Defender
Cybersecurity
Always-on protection for you and your family's data and devices
- From
- $12/month
- Rated
- -
The short version
- Only Tenable Nessus has a free tier, so it costs nothing to try first.
- Each has a real cost: Microsoft Defender defender Suite requires existing Microsoft 365 E3 or equivalent base licensing; Tenable Nessus nessus Professional is $4,790 for one year, sold as an annual licence rather than a per scan or usage based fee
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which Microsoft Defender and Tenable Nessus actually diverge.
| Attribute | Microsoft Defender | Tenable Nessus |
|---|---|---|
| Starting price | $12/month | Free |
| Free tier | No | Yes |
| Platforms | Web | Windows, Linux, Macos, Cloud |
| Founded | Unknown | 2002 |
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 Microsoft Defender
Nothing recorded that Tenable Nessus does not also cover.
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.
Microsoft Defender
- Endpoint security and threat protectionnot Tenable Nessus
- Identity and access securitynot Tenable Nessus
- Email threat protectionnot Tenable Nessus
- SaaS application security monitoringnot Tenable Nessus
Tenable Nessus
- Vulnerability scanning of servers, network devices and web applicationsnot Microsoft Defender
- Configuration and compliance auditing against hardening benchmarksnot Microsoft Defender
- Point in time assessments by consultants and penetration testersnot Microsoft Defender
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Microsoft Defender
- Defender Suite requires existing Microsoft 365 E3 or equivalent base licensing
- Some Defender products use pay-as-you-go pricing with variable costs
- Prices vary based on Microsoft agreements, requiring sales contact for custom quotes
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
Microsoft Defender
$12/month- Microsoft Defender Suite$12/month
- Endpoint protection
- Identity threat detection
- Email security
- Microsoft 365 E5 with Defender$60/month
- Includes Defender Suite
- Microsoft Teams included
- Comprehensive security and compliance
- Microsoft Defender Vulnerability Management Add-on$2/month
- Vulnerability scanning and management
- One-month free trial available
- Annual commitment required
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 Microsoft Defender if
Nothing in the data separates Microsoft Defender from Tenable Nessus on the points above - pick on price and on how each one feels to use.
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.
Questions people ask
- Is Microsoft Defender or Tenable Nessus better?
- Neither clearly leads. Microsoft Defender starts at $12/month and Tenable Nessus at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Microsoft Defender or Tenable Nessus?
- Tenable Nessus has a free tier; the other does not. Paid plans start at $12/month for Microsoft Defender and Free for Tenable Nessus.
- Does Microsoft Defender or Tenable Nessus run on more platforms?
- Microsoft Defender runs on Web. 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. Microsoft Defender starts at $12/month.
- What is Microsoft Defender best used for?
- Microsoft Defender is most often used for endpoint security and threat protection, identity and access security, email threat protection, saas application security monitoring. Of those, endpoint security and threat protection and identity and access security are not what Tenable Nessus is typically brought in for.
- What can Microsoft Defender do that Tenable Nessus cannot?
- Tenable Nessus covers Network scanning, Vulnerability detection, Configuration assessment, Malware detection.
Answered from the vendors’ own pages
Microsoft Defender: How much does Microsoft Defender Suite cost?
Microsoft Defender Suite costs $12/user/month (paid yearly), but requires existing Microsoft 365 E3 or equivalent base licensing. It includes endpoint protection, identity threat detection, email security, and SaaS application monitoring.
SourceTenable 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.
SourceMicrosoft Defender: What add-ons are available for Microsoft Defender?
Microsoft Defender Vulnerability Management Add-on costs $2/user/month with annual commitment and includes a one-month free trial. Additional pay-as-you-go products include External Attack Surface Management, Cloud Security Posture Management, and Sentinel.
SourceTenable 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.
SourceMicrosoft Defender: Is Defender included in Microsoft 365 E5?
Yes, Microsoft Defender Suite is included in Microsoft 365 E5 at $60/user/month (paid yearly with Teams). Prices may vary based on Microsoft agreements, requiring contact with Sales for customized quotes.
SourceTenable 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.
SourceTenable 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.
SourceTenable 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.
SourceTenable 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.
SourceTenable Nessus: How frequently are Nessus plugins updated?
Nessus plugins are updated daily, based on when vendors and security research sites publish new vulnerabilities.
SourceTenable 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.
SourceRelated pages
More on Microsoft Defender
More on Tenable Nessus
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