Company lists · Data refreshed September 2026

Top 25 Penetration testing services based in the United Kingdom

RevenueBase identified 354 company matches for penetration testing services associated with the United Kingdom as of September 2026 and tracks 3,874 professional contacts across them, including 992 with verified work emails. London is the largest hub.

This list covers company matches for penetration testing services associated with the United Kingdom, found by RevenueBase SmartSearch using the meaning of business descriptions in its company graph at Exact. Ranked by professionals tracked, largest first. Rows show recorded descriptions where available, Exact search membership and the snapshot date. Data refreshed September 21, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase SmartSearch, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list RevenueBase SmartSearch · Exact Recorded Sep 21, 2026 How this list was built
354Companies
3,874Contacts tracked
992Verified emails
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The 25 largest penetration testing services based in the United Kingdom

Ranked by team size
Top 25 of 354 company matches for penetration testing services based in the United Kingdom, ordered by professional contacts tracked in RevenueBase, largest first. Recorded Sep 21, 2026. The RevenueBase SmartSearch column shows Exact match membership in this saved search. Click a contact count to view that company's people. Totals use company locations recorded by RevenueBase; the displayed preview is a smaller selection.
#CompanyRevenueBase SmartSearchHeadquartersEmployeesContacts
1Exact matchThatcham, United KingdomHQ recorded Sep 21, 202651-200159 contacts →

Exact match

“At Cyberfort we are passionate about the cyber security services we deliver for our customers which keeps their people, data, systems and technology infrastructure secure…”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
2Exact matchLeeds, United KingdomHQ recorded Sep 21, 202651-20099 contacts →

Exact match

“AppCheck is a Complete Enterprise Security Testing Solution that provides up to the minute vulnerability coverage for your entire estate.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
3Exact matchOxford, United KingdomHQ recorded Sep 21, 202651-20073 contacts →

Exact match

“Dionach by Nomios has over 25 years of expertise in information security, supporting organisations in building resilience against ever‑evolving cyber threats.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
4Exact matchLondon, United KingdomHQ recorded Sep 21, 202651-20064 contacts →

Exact match

“YOU DESERVE TO BE HACKED®.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
5Exact matchLondon, United KingdomHQ recorded Sep 21, 202651-20061 contacts →

Exact match

“Intruder's continuous exposure management platform helps security, IT, and engineering teams stop breaches before they start.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
6Exact matchMacclesfield, United KingdomHQ recorded Sep 21, 202611-5061 contacts →

Exact match

“MDSec are a UK based consultancy with a passion for information security.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
7Exact matchLondon, United KingdomHQ recorded Sep 21, 202651-20051 contacts →

Exact match

“Redscan is an award-winning provider of managed security services, specialising in Managed Detection and Response, Penetration Testing and Red Teaming.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
8Exact matchBasingstoke, United KingdomHQ recorded Sep 21, 202651-20049 contacts →

Exact match

“Human-Led Continuous Testing.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
9Exact matchLondon, United KingdomHQ recorded Sep 21, 202651-20044 contacts →

Exact match

“Our Red Team security consultants are elite technical experts with worldwide Red Team service experience, and a respected reputation of delivering red team services for SME’s.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
10Exact matchBristol, United KingdomHQ recorded Sep 21, 202651-20039 contacts →

Exact match

“OnSecurity offers CREST-accredited AI Augmented Penetration Testing, all whilst harnessing technology to simplify the management and delivery of pentesting.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
11Exact matchCheadle, United KingdomHQ recorded Sep 21, 202651-20038 contacts →

Exact match

“Mitigo Group keeps professional services firms safe from cyberattack and operationally resilient.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
12Exact matchManchester, United KingdomHQ recorded Sep 21, 202611-5036 contacts →

Exact match

“Secarma exists to keep the world safe.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
13Exact matchLondon, United KingdomHQ recorded Sep 21, 202611-5036 contacts →

Exact match

“RedHunt Labs is a research-driven cybersecurity company delivering Continuous Threat Exposure Management (CTEM), PTaaS, and AI Exposure Security.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
14Exact matchCrawley, United KingdomHQ recorded Sep 21, 202611-5035 contacts →

Exact match

“ERGOS is an award-winning IT Managed Service Provider.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
15Exact matchCambridge, United KingdomHQ recorded Sep 21, 202611-5034 contacts →

Exact match

“Pentesting Exams by Pentesting Experts.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
16Exact matchLondon, United KingdomHQ recorded Sep 21, 20261,001-5,00033 contacts →

Exact match

“NotSoSecure Training, part of Claranet Cyber Security.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
17Exact matchStevenage, United KingdomHQ recorded Sep 21, 202651-20032 contacts →

Exact match

“Defense.com is transforming the way businesses manage cyber security by allowing them to easily identify, prioritise and remediate threats.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
18Exact matchBirmingham, United KingdomHQ recorded Sep 21, 202611-5032 contacts →

Exact match

“Aristi is a specialist provider of cyber security services with over 17 years of experience.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
19Exact matchCheltenham, United KingdomHQ recorded Sep 21, 202611-5031 contacts →

Exact match

“Salus is a provider of world-class cyber security services, enabling our clients to identify and manage their cyber risks proactively and effectively.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
20Exact matchLancaster, United KingdomHQ recorded Sep 21, 202611-5030 contacts →

Exact match

“Cyber security can feel overwhelming.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
21Exact matchPortsmouth, United KingdomHQ recorded Sep 21, 202611-5029 contacts →

Exact match

“Imagine a world where cyber threats are simply another challenge that you're fully equipped to handle.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
22Exact matchAltrincham, United KingdomHQ recorded Sep 21, 202611-5026 contacts →

Exact match

“Based in Manchester UK, we are an independent Cyber Security Consultancy providing Security services across a wide range of markets, from multi-national Corporate Organisations…”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
23Exact matchNewbury, United KingdomHQ recorded Sep 21, 202611-5023 contacts →

Exact match

“CyberCrowd are a market leader in the cyber security realm, offering everything from Assessment Services through to Pen Testing, CISOaaS, Certification Readiness, DPO services…”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
24Exact matchLondon, United KingdomHQ recorded Sep 21, 202611-5023 contacts →

Exact match

“Toro was founded on creating the UK's first Red Team penetration test - and then attacking hundreds of clients by hacking their systems, influencing / social engineering staff and…”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase
25Exact matchChester, United KingdomHQ recorded Sep 21, 202611-5022 contacts →

Exact match

“Protos Networks is an award-winning network and cyber security services specialist based in the North West of England.”

Recorded in the RevenueBase company graph · Sep 21, 2026 · View company records in RevenueBase

Showing 25 of 354 penetration testing services based in the United Kingdom

See the full list, filter by size, metro and specialty, and access 992 tracked professional contacts with verified work emails. Direct dials are available where recorded.

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Penetration testing services based in the United Kingdom at a glance

As of Sep 21, 2026
25.6%Verified-email coverage
10.9Average contacts per company
1-10Median size (employees)
37.3%Largest-city concentration · London
Sep 21, 2026Page data refreshed

Companies by employee count

1-10
221
11-50
103
51-200
20
201-500
3
501-1,000
2
1,001-5,000
5

Email recency for this list is measured worldwide rather than for United Kingdom, so it is reported there. Company counts and contact totals on this page are exact for United Kingdom, over 354 companies.

How this list was built

The recorded descriptions help you assess these company matches. Check a company’s website for its current services and locations.

Source
The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase SmartSearch, the natural-language company search available to every RevenueBase user.
What qualifies
Company records associated with the United Kingdom whose business descriptions match “penetration testing services” by meaning at the Exact setting. Descriptions are compiled in the RevenueBase company graph from public websites, profiles and company information where available; they are not guaranteed quotations from the company's website.
RevenueBase SmartSearch
Describe a niche company in your own words to find businesses by meaning. Exact, Similar, Related and Broad control the breadth of RevenueBase SmartSearch. This saved list uses Exact. Each row's Exact match badge shows inclusion in that search, not an individual score or a service-quality judgment.
Public preview
The public preview omits records without a verified work email. Where headquarters information is recorded, preview rows are also filtered to this page’s location. Dataset totals and geographic summaries describe the full matched records before these preview filters.
Match quality
RevenueBase's August 25, 2026 study assessed 4,198 description/company pairs across matching settings. The publisher reports 86% good or better at Exact. This evaluates the method across queries; it does not audit this individual list. Recorded company descriptions, where available, help you judge each match yourself. Read the full methodology: how the lists are built and what the study measures.
Ranking
Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification
Every displayed company carries at least one verified work email. RevenueBase tracks 992 professional contacts with verified work emails across the full matched dataset. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh
This page's figures were pulled from the company graph on September 21, 2026. Lists refresh periodically as the graph is re-checked.
Record context
Company records and descriptions can change. Check the company's website for its current services and locations.

Frequently asked

What is RevenueBase SmartSearch?

RevenueBase SmartSearch finds niche companies by the meaning of their business descriptions in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit your description. This list uses Exact for “penetration testing services”; each Exact match badge shows search membership, not an individual similarity or quality score.

How many penetration testing services are there based in the United Kingdom?

RevenueBase identified 354 company matches for penetration testing services associated with the United Kingdom as of September 2026, using the meaning of business descriptions at Exact. This is the recorded matched set in the RevenueBase company graph.

What is the largest company on this list?

Cyberfort tops the displayed preview by professional contacts tracked in RevenueBase. Recorded headquarters appear in the company rows.

Which city has the most penetration testing services?

London leads with 132 company records, followed by Manchester (21) and Birmingham (12).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work limited free results with 500 credits to start. Upgrading provides access to the 992 professional contacts with verified work emails tracked across these 354 companies; direct dials are available where recorded.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 21, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase SmartSearch, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.