The Best Penetration Testing Companies UK
The best UK penetration testing companies in 2026 are CREST-accredited firms with in-house testers, verifiable accreditations, and a clear retest policy. This guide compares 7 leading providers: Precursor Security, NCC Group, Pen Test Partners, Redscan (Kroll), JUMPSEC, OnSecurity, and Bulletproof, on criteria any buyer can check independently.
Seven CREST-accredited UK penetration testing companies compared on the criteria that actually matter to buyers: accreditation you can verify, pricing you can see before a sales call, retest policy, and where each firm genuinely excels.
We are Precursor Security, and we have ranked ourselves first on this list.
Rather than pretend otherwise, we publish the selection criteria in full, describe every competitor fairly, and link the independent CREST member directory so you can check our working. The firms below are genuinely good at what they do. The differences are in delivery model, transparency, and who each firm serves best.
Seven firms, side by side
| Company | CREST status | Pricing published | From | Retest policy published |
|---|---|---|---|---|
| 1. Precursor Security | Pen Test + VA + SOC | Yes | From £2,500 | Yes, included |
| 2. NCC Group | Member firm | No | On application | Not published |
| 3. Pen Test Partners | Member firm | No | On application | Not published |
| 4. Redscan (Kroll) | Member firm | No | On application | Not published |
| 5. JUMPSEC | Member firm + NCSC CHECK | No | On application | Not published |
| 6. OnSecurity | Member firm | No | Instant quote via platform | Not published |
| 7. Bulletproof | Member firm | No | On application | Not published |
Verified against each company's public website, June 2026. "Not published" means we could not find the policy publicly stated; it does not mean the firm lacks one.
The 7 best UK penetration
testing companies in 2026
1. Precursor Security
Precursor holds triple CREST accreditation across Penetration Testing, Vulnerability Assessment, and Security Operations Centre services, a combination held by fewer than 70 firms worldwide. Pricing is published on the website, from £2,500 for external network testing at approximately £1,250 per consultant day, with a retest included in every engagement and a written quote within 24 hours of scoping. Every tester is a UK-based, DBS-checked employee. The closed-loop model is the structural difference: penetration test findings feed directly into SOC detection rules for clients who use both services.
Trade-off: A mid-market specialist rather than a global enterprise brand, and the youngest firm on this list.
2. NCC Group
NCC Group is one of the largest security consultancies in the world, headquartered in Manchester, with a deep research pedigree and the capacity to staff very large, multi-region assessment programmes. For a FTSE-100 estate or a global rollout, few firms can match the bench depth.
Trade-off: Engagement model and pricing are built for enterprise procurement. Costs are on application.
3. Pen Test Partners
Pen Test Partners are the UK's best-known specialists in embedded and operational technology: connected vehicles, ships, planes, industrial control systems, and consumer IoT. Their public research is consistently excellent and widely cited. If your risk lives in hardware, they belong on your shortlist.
Trade-off: Specialist focus; standard web and infrastructure work is not their distinctive strength. Pricing on application.
4. Redscan (Kroll)
Redscan, now part of Kroll, pairs a large practitioner organisation with strong client review scores and the backing of a global incident response and forensics business. For organisations that want their tester, their IR retainer, and their forensics provider under one roof at enterprise scale, the Kroll relationship is the draw.
Trade-off: Pricing on application, and the engagement model leans enterprise.
5. JUMPSEC
JUMPSEC holds NCSC CHECK status alongside CREST membership, which makes them a strong choice for PSN-connected environments and government work that mandates CHECK delivery. Named private sector clients and published case studies add useful proof.
Trade-off: Pricing on application.
6. OnSecurity
OnSecurity runs a platform-first, pentest-as-a-service model with instant online quoting and quick scheduling, and carries strong review scores on G2. For a startup that needs a SaaS pen test booked this week with minimal procurement friction, the platform model works well.
Trade-off: Quotes are generated through their platform rather than published as a rate card, and the model is optimised for smaller, repeatable scopes.
7. Bulletproof
Bulletproof combines penetration testing with a broad compliance practice, including Cyber Essentials certification, which suits organisations that want testing and certification handled by a single supplier on one contract.
Trade-off: A generalist breadth play rather than a testing specialist. Pricing on application.
How we ranked them
Six criteria, each something a buyer should care about and can verify without taking anyone's word for it. Weighting is ours; the underlying facts are checkable.
Company accreditation in the CREST directory, and individual tester certification, not just an organisational badge. Accreditation at company and individual level means the people on your engagement passed practical exams.
Whether you can see rates before a sales call. POA pricing costs buyers days of procurement time and makes comparison impossible. One firm on this list publishes its rates.
In-house employed testers versus subcontracted or marketplace delivery. You should know who is actually inside your network.
Whether verification of your fixes is included or sold back to you afterwards as a second engagement.
How long between first contact and a written, fixed quote. Days versus weeks matters when an enterprise customer is waiting on your security questionnaire.
Where the firm genuinely excels. The right answer for connected vehicles is different from the right answer for a SaaS platform or a PSN-connected council.
Red flags when choosing
a pen test company
Whichever firm you choose, including us, walk away if you see these.
POA-only pricing with no rate guidance
A firm that cannot tell you its day rate before a discovery call is optimising for deal-size discovery, not your budget. UK CREST day rates run £1,000 to £1,500; anyone refusing to anchor near that range is hiding something, in either direction.
A scan dressed up as a pen test
Engagements priced under £500 per day are automated vulnerability scans with a human cover sheet. Ask directly: how many days of manual testing, by whom, with what certifications?
No named lead tester on the quote
You should know who is testing your systems before you sign: name, certification, employment status. Marketplace and subcontracted models often cannot tell you until the week of the test.
No retest provision
A pen test without verification of your fixes is half a service. If the retest is a separately priced second engagement, your remediation evidence for auditors and insurers costs double.
Accreditation claims that do not check out
Verify every CREST and CHECK claim against the official directories at crest-approved.org and ncsc.gov.uk. If a claim does not appear there, ask why before you proceed.
Reports written for machines, not boards
Ask for a redacted sample report before you buy. If it reads like raw scanner output with no executive summary, business impact, or prioritised remediation, your stakeholders will get nothing from it.
UK penetration testing prices in 2026
Across the market, CREST-accredited testing runs £1,000 to £1,500 per consultant day. At Precursor's published rate of approximately £1,250 per day: external network testing from £2,500, web application testing from £3,750, internal network testing from £6,250, and full multi-scope assessments from £10,000.
Full cost guide with worked examplesCompare us against anyone on this list.
Fixed pricing published before you call. A written quote within 24 hours of a scoping conversation. Retest included.
Choosing a pen test company
The questions buyers ask most when comparing UK providers.
UK penetration testing costs from £2,500 for a small external network test to £25,000+ for a full security assessment, at roughly £1,000 to £1,500 per consultant day from a CREST-accredited provider. A standard web application test runs £3,750 to £6,250 over 3 to 5 days; internal network testing for a single Active Directory domain starts around £6,250. Most firms on this list price on application; Precursor publishes its rates in a penetration testing cost guide.
CREST is the UK's independent accreditation body for offensive security providers, endorsed by the NCSC. Company accreditation means the firm's methodology, data handling, and complaint processes have been independently audited; individual certifications (CREST Registered Tester, Certified Tester) mean the people doing the work passed rigorous practical exams. Regulators, insurers, and enterprise procurement teams commonly require CREST-accredited testing.
Check the official CREST member directory at crest-approved.org. Search the company name and confirm which disciplines they are accredited for: penetration testing, vulnerability assessment, SOC, and incident response are separate accreditations. If a provider claims CREST status but does not appear in the directory, ask them to explain before you sign anything.
A vulnerability scan is an automated check that matches software versions against known-vulnerability databases and typically costs a few hundred pounds. A penetration test is a manual, human-led engagement in which accredited testers actively exploit weaknesses, chain findings together, and demonstrate real business impact. If a quote is under £500 per day, you are almost certainly buying a scan with a pen test label on it.
At least annually, and additionally after significant infrastructure changes, major application releases, mergers and acquisitions, or when a compliance framework or enterprise customer contract requires it. PCI DSS requires testing at least annually and after significant changes; many cyber insurance policies now expect the same cadence.