Company lists · Data refreshed September 2026

Top 25 Financial services security testing companies based in the United Kingdom

Name: Financial services security testing companies based in the United Kingdom
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 28, 2026 214 companies tracked

RevenueBase identified 214 financial services security testing companies headquartered in the United Kingdom as of September 2026 and tracks 2,966 professional contacts across them, including 651 with verified work emails. London is the largest hub.

This list covers financial services security testing companies headquartered in the United Kingdom, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 28, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, 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 HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 28, 2026 86% judged on-target in blind review

214Companies

2,966Contacts tracked

651Verified emails

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The 25 largest financial services security testing companies based in the United Kingdom

Ranked by team size

Top 25 of 214 financial services security testing companies based in the United Kingdom, ranked by team size, largest first. Data refreshed Sep 28, 2026. RevenueBase Smart Search rates how each company's information relates to financial services security testing companies: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	Appcheck LTD	Strong evidence	Leeds, United KingdomHQ checked Sep 28, 2026	51-200	99 contacts →
	Strong evidence “AppCheck is a Complete Enterprise Security Testing Solution that provides up to the minute vulnerability coverage for your entire estate.” Source: RevenueBase Database · checked Sep 28, 2026
2	Dionach By Nomios	Partial evidence	Oxford, United KingdomHQ checked Sep 28, 2026	51-200	73 contacts →
	Partial evidence “Dionach by Nomios has over 25 years of expertise in information security, supporting organisations in building resilience against ever‑evolving cyber threats.” Source: RevenueBase Database · checked Sep 28, 2026
3	MDSEC	Partial evidence	Macclesfield, United KingdomHQ checked Sep 28, 2026	11-50	61 contacts →
	Partial evidence “MDSec are a UK based consultancy with a passion for information security.” Source: RevenueBase Database · checked Sep 28, 2026
4	Secarma LTD	Indirect evidence	Manchester, United KingdomHQ checked Sep 28, 2026	11-50	36 contacts →
	Indirect evidence “Secarma exists to keep the world safe.” Source: RevenueBase Database · checked Sep 28, 2026
5	The Secops Group	Indirect evidence	Cambridge, United KingdomHQ checked Sep 28, 2026	11-50	34 contacts →
	Indirect evidence “Pentesting Exams by Pentesting Experts.” Source: RevenueBase Database · checked Sep 28, 2026
6	Notsosecure Training Part Of Claranet Cyber Security	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	1,001-5,000	33 contacts →
	Partial evidence “NotSoSecure Training, part of Claranet Cyber Security.” Source: RevenueBase Database · checked Sep 28, 2026
7	Aristi	Partial evidence	Birmingham, United KingdomHQ checked Sep 28, 2026	11-50	32 contacts →
	Partial evidence “Aristi is a specialist provider of cyber security services with over 17 years of experience.” Source: RevenueBase Database · checked Sep 28, 2026
8	Omnicyber Security	Partial evidence	Solihull, United KingdomHQ checked Sep 28, 2026	11-50	31 contacts →
	Partial evidence “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…” Source: RevenueBase Database · checked Sep 28, 2026
9	Procheckup PCU	Indirect evidence	Portsmouth, United KingdomHQ checked Sep 28, 2026	11-50	29 contacts →
	Indirect evidence “Imagine a world where cyber threats are simply another challenge that you're fully equipped to handle.” Source: RevenueBase Database · checked Sep 28, 2026
10	Cyber Security Specialists	Partial evidence	Altrincham, United KingdomHQ checked Sep 28, 2026	11-50	26 contacts →
	Partial evidence “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…” Source: RevenueBase Database · checked Sep 28, 2026
11	Ssl247 A Sectigo Company	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	51-200	24 contacts →
	Partial evidence “SSL247 (A Sectigo Company) has nearly 20 years of security consulting experience operating in 18 different markets globally.” Source: RevenueBase Database · checked Sep 28, 2026
12	Cybercrowd	Strong evidence	Newbury, United KingdomHQ checked Sep 28, 2026	11-50	23 contacts →
	Strong evidence “CyberCrowd are a market leader in the cyber security realm, offering everything from Assessment Services through to Pen Testing, CISOaaS, Certification Readiness, DPO services…” Source: RevenueBase Database · checked Sep 28, 2026
13	Toro Solutions	Indirect evidence	London, United KingdomHQ checked Sep 28, 2026	11-50	23 contacts →
	Indirect evidence “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…” Source: RevenueBase Database · checked Sep 28, 2026
14	Chaleit	Partial evidence	Cambridge, United KingdomHQ checked Sep 28, 2026	11-50	21 contacts →
	Partial evidence “Chaleit is a cyber security management consultancy that aligns business context with real-world capability to solve complex risks.” Source: RevenueBase Database · checked Sep 28, 2026
15	Secure Purple	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	11-50	20 contacts →
	Partial evidence “Secure Purple is a leading cyber security and digital safety firm that provides innovative solutions and services to help organisations and individuals stay protected in the…” Source: RevenueBase Database · checked Sep 28, 2026
16	Razorthorn Security	Partial evidence	Tunbridge Wells, United KingdomHQ checked Sep 28, 2026	11-50	19 contacts →
	Partial evidence “Razorthorn Security is a specialist cybersecurity consultancy founded in 2007, with nearly two decades of experience helping organisations protect their data, their systems and…” Source: RevenueBase Database · checked Sep 28, 2026
17	SE Labs	Partial evidence	Wimbledon, United KingdomHQ checked Sep 28, 2026	11-50	19 contacts →
	Partial evidence “We are dedicated to advancing cyber security through meticulous assessment of products and services engineered to detect and thwart cyber attacks.” Source: RevenueBase Database · checked Sep 28, 2026
18	Halo I.S	Indirect evidence	Leeds, United KingdomHQ checked Sep 28, 2026	11-50	19 contacts →
	Indirect evidence “Halo I.S is not just another cybersecurity organization based in the UK; we're a testament to evolution and client-centric innovation.” Source: RevenueBase Database · checked Sep 28, 2026
19	Assured Thought By Izertis	Indirect evidence	Shoreditch, United KingdomHQ checked Sep 28, 2026	51-200	15 contacts →
	Indirect evidence “Our focus is your quality.” Source: RevenueBase Database · checked Sep 28, 2026
20	Eh1-Infotech Cybersecurity	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	11-50	15 contacts →
	Partial evidence “is an ISO 9001:2015 and ISO/IEC 27001:2022 certified, DPIIT-recognized cybersecurity company delivering structured External Vulnerability Assessment & Penetration Testing (VAPT)…” Source: RevenueBase Database · checked Sep 28, 2026
21	Everycloud AI & Data Security	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	11-50	14 contacts →
	Partial evidence “Demand more from your AI & Data Security partner.” Source: RevenueBase Database · checked Sep 28, 2026
22	Safe Harbour Security	Strong evidence	Derry/londonderry, United KingdomHQ checked Sep 28, 2026	1-10	14 contacts →
	Strong evidence “Safe Harbour Security specialise in penetration testing, ISO consultancy, and governance, risk, and compliance (GRC) services.” Source: RevenueBase Database · checked Sep 28, 2026
23	Laburity	Partial evidence	Holborn, United KingdomHQ checked Sep 28, 2026	1-10	13 contacts →
	Partial evidence “Laburity: Cyber Security Research and Services Company.” Source: RevenueBase Database · checked Sep 28, 2026
24	Ruptura Infosecurity	Partial evidence	Milton Keynes, United KingdomHQ checked Sep 28, 2026	11-50	12 contacts →
	Partial evidence “We offer specialist CREST & CHECK Approved Penetration Testing services in order to secure our clients most critical assets.” Source: RevenueBase Database · checked Sep 28, 2026
25	Cyber Guarded LTD	Strong evidence	Belfast, United KingdomHQ checked Sep 28, 2026	11-50	12 contacts →
	Strong evidence “Cyber Guarded is a vendor independent business which provides Cyber Security auditing and testing services.” Source: RevenueBase Database · checked Sep 28, 2026

RevenueBase Smart Search

RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: financial services security testing companies. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.

Strong evidence: The company's own public description of its business names financial services security testing companies.
Partial evidence: Its own public description names part of financial services security testing companies, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name financial services security testing companies. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.

RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.

Showing 25 of 214 financial services security testing companies based in the United Kingdom

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Financial services security testing companies based in the United Kingdom at a glance

As of Sep 28, 2026

21.9%Verified-email coverage

13.9Average contacts per company

1-10Median size (employees)

34.1%Largest-city concentration · London

Sep 28, 2026Page data refreshed

Companies by employee count

1-10

126

11-50

51-200

201-500

501-1,000

1,001-5,000

5,001-10,000

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 214 companies.

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among financial services security testing companies, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source: The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
What qualifies: Companies headquartered in the United Kingdom whose own description of what they do matches “financial services security testing companies”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search: RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names financial services security testing companies), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude: Companies whose own description does not clearly place them among financial services security testing companies, and records with no verified work email. Companies headquartered outside United Kingdom are excluded even when they keep an office there.
Match quality: In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
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 listed company carries at least one verified work email, 651 across the full list. 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 28, 2026. Lists refresh periodically as the graph is re-checked.
Corrections: Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

Financial services security testing companies by metro

Financial services security testing companies in London73

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names financial services security testing companies, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many financial services security testing companies are there based in the United Kingdom?

RevenueBase identified 214 financial services security testing companies headquartered in the United Kingdom as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

Appcheck LTD, headquartered in Leeds, tops this list with the largest team on record.

Which city has the most financial services security testing companies?

London leads with 73 headquartered companies, followed by Manchester (13) and Birmingham (8).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 651 verified decision-maker contacts tracked across these 214 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 28, 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 Smart Search, 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.