Company lists · Data refreshed September 2026

Top 25 Security testing service providers based in the United Kingdom

RevenueBase identified 420 company matches for security testing service providers associated with the United Kingdom as of September 2026 and tracks 4,445 professional contacts across them, including 1,272 with verified work emails. London is the largest hub.

This list covers company matches for security testing service providers 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 29, 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 29, 2026 How this list was built
420Companies
4,445Contacts tracked
1,272Verified emails
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The 25 largest security testing service providers based in the United Kingdom

Ranked by team size
Top 25 of 420 company matches for security testing service providers based in the United Kingdom, ordered by professional contacts tracked in RevenueBase, largest first. Recorded Sep 29, 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 matchKnutsford, United KingdomHQ recorded Sep 29, 202651-200267 contacts →

Exact match

“PortSwigger is a global leader in the creation of software tools for security testing of web applications.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
2Exact matchLeeds, United KingdomHQ recorded Sep 29, 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 29, 2026 · View company records in RevenueBase
3Exact matchStourport-on-severn, United KingdomHQ recorded Sep 29, 2026201-50086 contacts →

Exact match

“CyberGuard Technologies is the security division of Wavenet.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
4Exact matchWaterloo, United KingdomHQ recorded Sep 29, 202651-20080 contacts →

Exact match

“At Reliance Cyber, we believe in truly partnering with our customers.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
5Exact matchOxford, United KingdomHQ recorded Sep 29, 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 29, 2026 · View company records in RevenueBase
6Exact matchLondon, United KingdomHQ recorded Sep 29, 202651-20064 contacts →

Exact match

“YOU DESERVE TO BE HACKED®.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
7Exact matchDoncaster, United KingdomHQ recorded Sep 29, 202651-20062 contacts →

Exact match

“At DigitalXRAID, we’re more than just a managed security services provider – we’re your trusted partner in safeguarding your business from cyber threats.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
8Exact matchMacclesfield, United KingdomHQ recorded Sep 29, 202611-5061 contacts →

Exact match

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

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
9Exact matchLondon, United KingdomHQ recorded Sep 29, 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 29, 2026 · View company records in RevenueBase
10Exact matchBasingstoke, United KingdomHQ recorded Sep 29, 202651-20049 contacts →

Exact match

“Human-Led Continuous Testing.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
11Exact matchCardiff, United KingdomHQ recorded Sep 29, 202611-5049 contacts →

Exact match

“PureCyber is an award-winning, expert Cyber Security Consultancy.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
12Exact matchCheltenham, United KingdomHQ recorded Sep 29, 202651-20042 contacts →

Exact match

“CoreTech is a specialist cyber security company whose people are motivated by the desire to deliver exceptional capabilities coupled with a real sense of mission.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
13Exact matchCirencester, United KingdomHQ recorded Sep 29, 202611-5039 contacts →

Exact match

“We help organisations understand, optimise, and strengthen their cybersecurity.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
14Exact matchCorsham, United KingdomHQ recorded Sep 29, 202611-5039 contacts →

Exact match

“Computer Network Defence Ltd are a UK based cyber security consultancy with an extremely broad spectrum of capability.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
15Exact matchSaffron Walden, United KingdomHQ recorded Sep 29, 202651-20038 contacts →

Exact match

“Omerta - A Global Security Technology and Services Company.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
16Exact matchCheadle, United KingdomHQ recorded Sep 29, 202651-20038 contacts →

Exact match

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

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
17Exact matchManchester, United KingdomHQ recorded Sep 29, 202611-5036 contacts →

Exact match

“Secarma exists to keep the world safe.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
18Exact matchLondon, United KingdomHQ recorded Sep 29, 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 29, 2026 · View company records in RevenueBase
19Exact matchCrawley, United KingdomHQ recorded Sep 29, 202611-5035 contacts →

Exact match

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

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
20Exact matchCambridge, United KingdomHQ recorded Sep 29, 202611-5034 contacts →

Exact match

“Pentesting Exams by Pentesting Experts.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
21Exact matchLondon, United KingdomHQ recorded Sep 29, 20261,001-5,00033 contacts →

Exact match

“NotSoSecure Training, part of Claranet Cyber Security.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
22Exact matchStevenage, United KingdomHQ recorded Sep 29, 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 29, 2026 · View company records in RevenueBase
23Exact matchBirmingham, United KingdomHQ recorded Sep 29, 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 29, 2026 · View company records in RevenueBase
24Exact matchCheltenham, United KingdomHQ recorded Sep 29, 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 29, 2026 · View company records in RevenueBase
25Exact matchLancaster, United KingdomHQ recorded Sep 29, 202611-5030 contacts →

Exact match

“Cyber security can feel overwhelming.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase

Showing 25 of 420 security testing service providers based in the United Kingdom

See the full list, filter by size, metro and specialty, and access 1,272 tracked professional contacts with verified work emails. Direct dials are available where recorded.

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Security testing service providers based in the United Kingdom at a glance

As of Sep 29, 2026
28.6%Verified-email coverage
10.6Average contacts per company
1-10Median size (employees)
37.1%Largest-city concentration · London
Sep 29, 2026Page data refreshed

Companies by employee count

1-10
250
11-50
130
51-200
26
201-500
5
501-1,000
3
1,001-5,000
4
5,001-10,000
1

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 420 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 “security testing service providers” 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 1,272 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 29, 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.

Security testing service providers by metro

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 “security testing service providers”; each Exact match badge shows search membership, not an individual similarity or quality score.

How many security testing service providers are there based in the United Kingdom?

RevenueBase identified 420 company matches for security testing service providers 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?

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

Which city has the most security testing service providers?

London leads with 156 company records, followed by Manchester (23) and Birmingham (11).

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 1,272 professional contacts with verified work emails tracked across these 420 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 29, 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.