OnScanner vs Tenable Nessus
Tenable Nessus is a long-established vulnerability scanner, built around credentialed, inside-out auditing of assets you own. OnScanner looks at the same estate from the opposite direction: what an anonymous attacker can see and probe from the public internet, including the privacy, email, TLS and WAF posture that vulnerability management tools do not cover. This is closer to a pairing than a rivalry.
Evaluating options? See OnScanner as a Nessus alternative.
TL;DR
Choose OnScanner when you want the attacker's outside-in view of your web presence in one fully automated pass: live, never-cached scans with safe exploit verification and zero-day heuristics, EPSS and CISA KEV prioritization, deep technology and end-of-life detection, and 40+ privacy and tracker checks with email, TLS and WAF posture. Turn on AI Findings and it writes the executive summary, ranks your Top Risks, chains findings into MITRE ATT&CK attack paths, drafts remediation, and generates SOC 2, ISO 27001, GDPR, PCI-DSS and HIPAA compliance reports. Free tier and a hosted MCP server included.
Tenable Nessus is a great choice when you own the infrastructure and need deep credentialed auditing: missing patches, configuration and compliance checks against CIS benchmarks, across your full asset inventory. Many teams run both: Nessus inside, OnScanner outside.
Feature comparison
Verified against public product pages on 2026-07-02. Cells marked "Not listed" mean the capability is not described on the vendor's public docs as of that date, not that it is impossible.
| Capability | OnScanner | Tenable Nessus |
|---|---|---|
| External (unauthenticated) scanning | YesThe anonymous attacker's view, no agents | YesSupported; external attack-surface discovery is Expert-only (5 domains/quarter) |
| Authenticated scanning | YesScan behind login with credentials | YesCore competency: credentialed scans 'discover any missing patches' |
| Privacy, tracker & consent scanning | Yes40+ categories incl. fingerprinting | NoNo tracker, cookie, consent, or fingerprinting detection appears anywhere on Nessus product pages |
| CVE intelligence (EPSS & CISA KEV) | YesCVE/CPE matching with EPSS + KEV context | YesVulnerability prioritization using CVSS v4, EPSS, and Tenable VPR is marketed on the product page |
| Active exploit verification | YesSafe, non-destructive, in-band probes | NoNessus detects: plugins contain 'the algorithm to test for the presence of the security issue' |
| Patch-status & end-of-life detection | YesVendor/distro patch data + EOL flags | YesCredentialed patch auditing is the flagship capability |
| Email security (SPF, DKIM, DMARC) | Yes | PartialSPF plugin and CIS audit items exist; not a marketed capability |
| WAF detection | Yes | NoWAF fingerprinting is not marketed anywhere on Nessus product pages |
| Continuous monitoring | YesScheduled scans + change detection | PartialScheduling + Live Results; continuous exposure mgmt lives in Tenable One/VM |
| REST API | Yes | PartialAPI keys + exports; scan launch via API requires Tenable SC/VM platform |
| MCP server for AI agents | YesHosted: mcp.onscanner.com | PartialTenable Hexa AI MCP (GA May 2026) requires a Tenable One license, not standalone Nessus |
| AI analysis, remediation & compliance reports | YesOpt-in AI Findings + AI Compliance (SOC 2, ISO 27001, GDPR, PCI-DSS, HIPAA) | PartialTenable Hexa AI and its MCP require a Tenable One license, not standalone Nessus |
| Transparent self-serve pricing | YesFree tier; Professional $60/mo | YesPublic list prices for Professional and Expert with online purchase, multi-year terms, and a free trial |
Why teams pick OnScanner
- Enterprise-grade coverage, fully automated: specialist engines for security, privacy, CVE, DNS, technology and infrastructure analysis run in parallel on every scan, with no agents or appliances to deploy.
- Every scan is live and never cached, with safe active exploitation probes that verify what is actually exploitable and zero-day heuristics that flag unknown vulnerabilities before a CVE exists.
- Deep technology detection with patch-status and end-of-life flags, so you know exactly what is running and what is out of support.
- Exploit-aware prioritization: CVE and CPE matching enriched with EPSS scores and the CISA KEV catalog, so you fix what attackers actually use.
- Opt-in AI Findings: an executive summary, ranked Top Risks, and clear per-finding explanations with remediation your developers can act on.
- Vulnerability chaining: AI Findings links related results into real attack paths mapped to the MITRE ATT&CK kill chain.
- AI Compliance reports on demand: SOC 2, ISO 27001, GDPR, PCI-DSS and HIPAA assessments generated from your scan results.
- 40+ privacy, tracker, fingerprinting and consent checks plus email (SPF, DKIM, DMARC), TLS and WAF posture in the same pass.
- Continuous monitoring with scheduled scans and 24/7 change detection, plus a REST API and hosted MCP server on every plan, free tier included.
When Tenable Nessus fits
- You own the assets and need the inside-out picture: credentialed patch auditing plus configuration and compliance checks against CIS benchmarks, from a plugin library updated daily.
- You are a consultant, pentester, or SMB that wants unlimited vulnerability assessments at a flat published price, with pre-configured scan templates.
- You want risk prioritization based on CVSS v4, EPSS, and Tenable VPR, with an upgrade path into Tenable One exposure management.
Already running Nessus? OnScanner is the natural outside-in companion: live web scans with 40+ privacy and tracker checks, email, TLS and WAF posture, and opt-in AI compliance reports, with no agents to deploy.
Pricing
Both vendors publish real prices, which is rarer than it should be in this market. OnScanner is self-serve with a free Starter tier and Professional at $60 per month. Nessus Professional lists at $4,790 per year and Nessus Expert at $6,790 per year (verified 2026-07-02). The scopes differ: Nessus prices unlimited credentialed IT scanning across your assets; OnScanner prices live outside-in web scanning per target.
Frequently asked questions
Does OnScanner replace Nessus?
Not if you rely on credentialed patch and compliance auditing of assets you own: that is Nessus's core strength and OnScanner deliberately does not install agents or take credentials for host auditing. If your need is the outside-in web picture (vulnerabilities, privacy, email, TLS, WAF), OnScanner covers ground Nessus does not.
Can I use OnScanner and Nessus together?
Yes, and it is a natural pairing. Nessus gives you the inside-out inventory of missing patches and misconfigurations on hosts you control. OnScanner gives you the live external view an attacker gets, plus privacy and email posture. Together they cover both vantage points.
Which tool finds more vulnerabilities?
A credentialed scanner will always report more raw findings on hosts you own, because it can read local package data. OnScanner reports what is actually reachable and verifiable from the outside, prioritized with EPSS and KEV, plus categories vulnerability management tools do not scan at all, like trackers and consent behavior.
Do both work with AI agents?
OnScanner ships a hosted MCP server (mcp.onscanner.com) on every plan, so Claude, Cursor, and other agents can run scans directly. Tenable's Hexa AI MCP server is generally available but requires a Tenable One license and runs through Tenable Vulnerability Management rather than standalone Nessus.
Sources
Every Tenable Nessus fact above was checked against these public pages on 2026-07-02. If something has changed since, tell us at support@onscanner.com and we will correct it.
- Tenable Nessus product page
- Nessus Professional (Tenable)
- Nessus Expert (Tenable)
- Nessus FAQ (Tenable)
- Hexa AI MCP getting-started docs (Tenable)
- Hexa AI press release (Tenable)
- Tenable Hexa AI MCP coverage (SiliconANGLE)
- CISA directive 22-01 and KEV blog post (Tenable)
- Nessus plugin 31658 (Tenable)
- Nessus API key docs (Tenable)
See what OnScanner finds on your site
Live, never-cached security and privacy scanning: OWASP Top 10, CVE intelligence with EPSS and KEV, 40+ privacy checks, REST API and MCP server. Free Starter tier, no sales call.