Company lists · Data refreshed September 2026

Top 25 Vendor security assessment firms based in the United Kingdom

RevenueBase identified 247 company matches for vendor security assessment firms associated with the United Kingdom as of September 2026 and tracks 2,522 professional contacts across them, including 596 with verified work emails. London is the largest hub.

This list covers company matches for vendor security assessment firms 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
247Companies
2,522Contacts tracked
596Verified emails
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The 25 largest vendor security assessment firms based in the United Kingdom

Ranked by team size
Top 25 of 247 company matches for vendor security assessment firms 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 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
2Exact matchLondon, United KingdomHQ recorded Sep 29, 2026201-50097 contacts →

Exact match

“As an independent IT security specialist, Caretower provide comprehensive solutions to individual problems, thus allowing our recommendations to be unbiased.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
3Exact 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
4Exact matchAlderley Edge, United KingdomHQ recorded Sep 29, 202651-20057 contacts →

Exact match

“CyberLab is the UK-leading cyber security consultancy and managed services provider, trusted by over 1,200 enterprise businesses, government departments, and household names to…”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
5Exact 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
6Exact 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
7Exact 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
8Exact 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
9Exact matchSolihull, United KingdomHQ recorded Sep 29, 202611-5031 contacts →

Exact match

“SPECIALISTS IN IT SECURITY AND COMPLIANCE Our goal is to help customers define, develop and implement information security and compliance services, no matter what stage of the…”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
10Exact matchPortsmouth, United KingdomHQ recorded Sep 29, 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 29, 2026 · View company records in RevenueBase
11Exact matchAltrincham, United KingdomHQ recorded Sep 29, 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 29, 2026 · View company records in RevenueBase
12Exact matchNewbury, United KingdomHQ recorded Sep 29, 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 29, 2026 · View company records in RevenueBase
13Exact matchLondon, United KingdomHQ recorded Sep 29, 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 29, 2026 · View company records in RevenueBase
14Exact matchCambridge, United KingdomHQ recorded Sep 29, 202611-5021 contacts →

Exact match

“Chaleit is a cyber security management consultancy that aligns business context with real-world capability to solve complex risks.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
15Exact matchLondon, United KingdomHQ recorded Sep 29, 202611-5020 contacts →

Exact match

“LMS Security are a fully Independent, privately owned, Internationally recognised and accredited Security Consultancy; owned and built by Electronic and Physical Security…”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
16Exact matchTunbridge Wells, United KingdomHQ recorded Sep 29, 202611-5019 contacts →

Exact match

“Razorthorn Security is a specialist cybersecurity consultancy founded in 2007, with nearly two decades of experience helping organisations protect their data, their systems and…”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
17Exact matchLeeds, United KingdomHQ recorded Sep 29, 202611-5019 contacts →

Exact match

“Halo I.S is not just another cybersecurity organization based in the UK; we're a testament to evolution and client-centric innovation.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
18Exact matchLondon, United KingdomHQ recorded Sep 29, 20261-1017 contacts →

Exact match

“Cyber Security Assessment, Score Carding, Benchmarking, and Risk Management Platform.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
19Exact matchLondon, United KingdomHQ recorded Sep 29, 202651-20015 contacts →

Exact match

“Who We Are DataSixth delivers Cybersecurity Intelligence.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
20Exact matchLondon, United KingdomHQ recorded Sep 29, 202611-5015 contacts →

Exact match

“is an ISO 9001:2015 and ISO/IEC 27001:2022 certified, DPIIT-recognized cybersecurity company delivering structured External Vulnerability Assessment & Penetration Testing (VAPT)…”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
21Exact matchLondon, United KingdomHQ recorded Sep 29, 202611-5014 contacts →

Exact match

“Demand more from your AI & Data Security partner.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
22Exact matchDerry/londonderry, United KingdomHQ recorded Sep 29, 20261-1014 contacts →

Exact match

“Safe Harbour Security specialise in penetration testing, ISO consultancy, and governance, risk, and compliance (GRC) services.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
23Exact matchMilton Keynes, United KingdomHQ recorded Sep 29, 202611-5012 contacts →

Exact match

“We offer specialist CREST & CHECK Approved Penetration Testing services in order to secure our clients most critical assets.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
24Exact matchBelfast, United KingdomHQ recorded Sep 29, 202611-5012 contacts →

Exact match

“Cyber Guarded is a vendor independent business which provides Cyber Security auditing and testing services.”

Recorded in the RevenueBase company graph · Sep 29, 2026 · View company records in RevenueBase
25Exact matchWinchester, United KingdomHQ recorded Sep 29, 202611-5012 contacts →

Exact match

“Security Consultants at Infosec Partners are formally trained to a high degree, having at least one of the following Security Management certifications: CESG CLAS, CISSP, CISM…”

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

Showing 25 of 247 vendor security assessment firms based in the United Kingdom

See the full list, filter by size, metro and specialty, and access 596 tracked professional contacts with verified work emails. Direct dials are available where recorded.

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Vendor security assessment firms based in the United Kingdom at a glance

As of Sep 29, 2026
23.6%Verified-email coverage
10.2Average contacts per company
1-10Median size (employees)
33.6%Largest-city concentration · London
Sep 29, 2026Page data refreshed

Companies by employee count

1-10
160
11-50
67
51-200
13
201-500
3
501-1,000
3
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 247 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 “vendor security assessment firms” 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 596 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.

Vendor security assessment firms 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 “vendor security assessment firms”; each Exact match badge shows search membership, not an individual similarity or quality score.

How many vendor security assessment firms are there based in the United Kingdom?

RevenueBase identified 247 company matches for vendor security assessment firms 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?

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

Which city has the most vendor security assessment firms?

London leads with 83 company records, followed by Birmingham (9) and Manchester (7).

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 596 professional contacts with verified work emails tracked across these 247 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.