Intruder vs Tenable
This comparison is unusual because the two products are not fully independent: Intruder documents that its Pro tier is powered by the commercial Tenable Nessus engine. So the real question is not whose detection is better — at that tier it is the same engine — but whether Intruder's workflow around it is worth the difference over licensing Nessus directly. Tenable also sells well beyond Nessus, which is where the comparison genuinely diverges.
Key Facts
- →Intruder documents its Pro tier as powered by the Tenable Nessus engine (>141,000 external and >14,000 internal checks).
- →Nessus Professional lists at $4,790 for one year on tenable.com, with $400 optional Advanced Support.
- →Intruder does not publish plan prices: the model is a base fee plus a per-target fee, sized by target count.
- →Intruder counts as a target every external IP, domain, sub-domain, container image and agent-installed device.
- →Tenable's enterprise line (Vulnerability Management, formerly Tenable.io) is quote-based and aimed at large estates.
Quick Comparison
| Aspect | Intruder | Tenable |
|---|---|---|
| Detection engine at comparable tier | Tenable NessusTie | Tenable NessusTie |
| Published pricing | No: base fee plus per target | Yes for Nessus Professional ($4,790/yr)✓ Advantage |
| Asset and cloud discovery | Included✓ Advantage | Enterprise tiers only |
| Setup and maintenance effort | Low: managed✓ Advantage | You run and tune it |
| Free tier | Yes: 5 web apps, 1 cloud account, 3 usersTie | Nessus Essentials, 16 IPsTie |
| Enterprise-scale estates | Grows expensive per target | Built for it✓ Advantage |
| Web application coverage | ZAP-based add-on (~100 checks)Tie | Web App Scanning sold separatelyTie |
| Human penetration testing | Vanguard tier✓ Advantage | Not part of the scanner line |
| Cost predictability | Depends on how you count targets | Fixed licence for Nessus Pro✓ Advantage |
| Access control and logic flaws | NoTie | NoTie |
What You Can Actually Price (2026)
Only published figures. Where a vendor quotes instead of listing, the cell says so rather than carrying an estimate.
| Option | Published price | What it is |
|---|---|---|
| Nessus Essentials | Free (16 IPs) | Scanner, tiny estates |
| Nessus Professional | $4,790 / year | Unlimited-IP scanner, one user |
| Nessus Professional, 3 years | $13,637.54 | ~$4,546 per year |
| Tenable Vulnerability Management | Quote | Enterprise VM platform |
| Intruder Free | Free | 5 web apps, 1 cloud account, 3 users |
| Intruder Cloud / Pro / Enterprise | Not published | Base fee plus per-target fee |
| Intruder AI pentesting add-on | From $3,500 per test | Per test |
Nessus prices from tenable.com; Intruder plan engines, target definition and the $3,500 figure from intruder.io and help.intruder.io. Checked August 2026.
What is Intruder?
Vulnerability scanning and attack-surface monitoring delivered as a managed platform: asset and cloud discovery, scheduling, emerging-threat scans, triage and reporting, with the Pro tier running the Tenable Nessus engine underneath. Higher tiers add continuous network scanning and, at Vanguard, human penetration testing.
What is Tenable?
The vendor behind Nessus. Nessus Professional is a per-licence scanner with unlimited IPs for one user and a published price; the enterprise products (Vulnerability Management, Security Center) add asset management, dashboards, risk scoring and multi-user workflow at quote-based pricing.
The Same Engine, Different Products
Because Intruder Pro runs Nessus, the detection comparison largely dissolves: at that tier you are buying the same checks. What Intruder adds is everything around them — discovery of assets you forgot, scheduling, emerging-threat sweeps when something notable drops, triage that filters the report, and a UI a non-specialist can act on. What you pay for that is the difference between your Intruder quote and $4,790.
That framing makes the decision tractable. Get the quote, subtract the Nessus baseline, and ask whether the remainder buys enough workflow for your team. For a team without a dedicated security engineer, it often does: somebody has to notice the new subdomain and schedule the scan, and if nobody does, the licence is cheaper and worthless. For a team that already runs Nessus competently, the wrapper is harder to justify.
Where the Per-Target Model Bites
Intruder counts every external IP, domain, sub-domain, container image and agent-installed device as a target, and the price scales with the count. That is fair — it reflects work — but it punishes untidy estates. Forty stale sub-domains from old campaigns are forty targets on your invoice.
So audit before you ask for a quote: retire dead DNS records, consolidate redundant hostnames, decide which container images actually need standing scans. Teams routinely cut their target count materially in an afternoon, and the same tidy-up shrinks their real attack surface, which is the point of the exercise anyway.
Nessus Professional prices per licence rather than per asset, so an untidy estate costs you nothing extra there — it just costs you the analyst time to sort the results, which is the trade you are making.
What Neither Covers
Both are infrastructure-first. They find missing patches, weak configurations, exposed services and known CVEs, and they are good at it. Neither will tell you that one tenant can read another tenant's records, because that is not a signature — it depends on what your application is supposed to allow.
Intruder's web application coverage is a ZAP-based add-on of roughly 100 checks; Tenable sells Web App Scanning separately. Both are signature-level web coverage, not application testing. If your crown jewels sit behind application logic, treat the pentest budget as a separate line item rather than something either scanner absorbs.
When to Choose Each
Choose Intruder when…
- →You have no dedicated security engineer and need the scanning to run itself.
- →You want asset and cloud discovery included rather than bolted on.
- →Your estate is small enough that per-target pricing stays comfortable.
- →You want the option of human pentesting from the same vendor (Vanguard).
Choose Tenable when…
- →You want a published price and predictable renewal.
- →Your estate is large enough that per-target pricing would hurt.
- →You already have someone who runs scanners and triages output.
- →You need enterprise asset management, risk scoring and multi-user workflow.
Can You Use Both?
Rarely worth it: at the Pro tier you would be paying twice for the same engine. The sensible pairing is one of these for infrastructure and something application-layer alongside it, because that is the real gap rather than the overlap.
Verdict
Treat it as platform versus licence, not detection versus detection. If nobody on your team will own scanning, Intruder's wrapper is worth real money and the free tier is a genuine way to start. If you have the capability in-house, Nessus Professional at $4,790 a year gives you the same engine with a price you can plan around. Either way, budget the analyst time — the licence is the cheap part — and buy application-layer testing separately.Work out your own numbers in the cost calculator→
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