Best Vulnerability Scanners for Startups & SMEs (Under $500/mo)

(Real-World Picks from Someone Who Talks at B-Sides and Pays the Mortgage at IBM)

Hey everyone, Gareth here — most of you will know me from the B-Sides circuit (London 2023 & 2024 speaker, did the “Nuclei vs the World” talk that apparently broke the room in Manchester, and yes, I’m the guy who keeps getting dragged on stage at SteelCon and BSides Leeds because I won’t shut up about fast, cheap scanning).

By day I’m a Principal Security Architect at IBM — which means I get to play with the multi-million-dollar enterprise toys.
By night (and on weekends) I advise bootstrapped startups and scale-ups who have exactly £400 a month to spend on security and still need to pass a customer audit before their next funding round.This list is what I actually recommend when a founder corners me after a B-Sides talk and whispers “Mate, I can’t afford Nessus… what do I do?”All prices checked November 20, 2025 — everything here is genuinely under $500/month (most are under $200, several are free).

The “I’ve Used These On Real Clients” Comparison Table

The Deep Dive – What I Tell People Over a Beer After My Talk

1. Nuclei – The Tool That Made Me Stop Apologising for Free Tools

Every single B-Sides talk I give now has at least 20 minutes on Nuclei.
Why? Because in 2025 the community templates find more real bugs than most $25k/year commercial scanners I’m forced to use at $BigCorp.

• Run it yourself on a £5/month VPS → unlimited targets, zero cost

• Or pay ProjectDiscovery $199/mo for their cloud dashboard and never think about it again

• Zero false positives when you stick to signed/verified templates

• Finds stuff the commercial tools still miss (I’m looking at you, latest Spring Cloud Function RCE)

If you only take one thing from this article (or my talk), install Nuclei. Today.

2. Intruder.io – The One I Secretly Put All My Startup Clients OnHands-down the best “I have no security team” solution under £500/mo.I’ve had founders literally hug me when they saw the Slack integration and the “3 critical issues — here’s screenshots and fix guidance” report.
Uses Nuclei + their own magic under the hood, but with a UI your intern can understand.

3. OWASP ZAP Headless – Still Free, Still RelevantI still demo this live on stage because the audience gasps when they see authenticated scanning of a React SPA for £0.Stick it in your GitHub Actions, scan every push, sleep at night.

4. Prowler – The Free Cloud Posture Tool IBM Wishes It Had BuiltEvery startup I speak to at conferences has at least one public S3 bucket.
Prowler finds it in 90 seconds and generates a PDF your investors will actually read.The Tools I Tell Founders to Run Away From (Politely, Because I’m On Stage)

• Nessus — great when IBM pays, terrible when you do

• Qualys — per-asset pricing will murder a startup

• Burp Scanner — buy Burp Pro for manual work, not automated scanning

• Anything that costs four figures a year and still phones home to Tennessee

My Exact Post-Talk Recommendation (Depending on Your Burn Rate)Just raised angel round, £0 security budget?
→ Nuclei (self-hosted) + ZAP in CI + Prowler = better than most Series A companiesGot £150–£250/mo from that YC cheque?
→ Intruder Starter or Probely + ProwlerSeries A, SOC 2 looming, investors asking questions?
→ Intruder Pro or Detectify top-tier — pretty reports that make auditors smile, I’ve given this exact advice to over 60 founders in the last 18 months. Zero of them have been breached (that I know of).So yeah — you don’t need an enterprise budget to not get pwned in 2025.See you at the next B-Sides. First round’s on me if you tell me you actually implemented one of these.— Gareth (the loud one from IBM who keeps banging on about Nuclei)
B-Sides London, Manchester, Leeds, SteelCon speaker | IBM Principal Security Architect by day | Startup security whisperer by night
November 20, 2025