Company lists · Data refreshed August 2026
Top 25 Computer security companies based in the United Kingdom
RevenueBase identified 310 computer security companies headquartered in the United Kingdom as of August 2026 and tracks 8,567 professional contacts across them, including 4,089 with verified work emails and 1,109 with mobile numbers. London is the largest hub.
This list covers computer security 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 August 31, 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.
The 25 largest computer security companies based in the United Kingdom
Ranked by team size| # | Company | Contacts | |||
|---|---|---|---|---|---|
| 1 | 4,963 contacts → | ||||
Indirect evidence “Sophos is a cybersecurity leader defending organizations globally with an AI-driven platform and expert-led services.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 2 | 739 contacts → | ||||
Partial evidence “SISA is a global forensics-driven cybersecurity solutions company, trusted by leading organizations for securing their businesses with robust preventive, detective, and corrective…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 3 | 292 contacts → | ||||
Indirect evidence “At Quorum Cyber, we're on a mission to help good people win.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 4 | 160 contacts → | ||||
Partial evidence “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…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 5 | 135 contacts → | ||||
Partial evidence “At Cipher, we're redefining digital security as the premier cybersecurity leader in the Middle East.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 6 | 129 contacts → | ||||
Partial evidence “KHIPU Networks is an award winning international Cyber Security Company delivering a wide range of network, wireless and security solutions, technologies and services across…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 7 | 118 contacts → | ||||
Indirect evidence “Bulletproof is now part of WorkNest Secure.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 8 | 100 contacts → | ||||
Indirect evidence “As the world becomes more connected, our lives and businesses are more vulnerable.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 9 | 89 contacts → | ||||
Partial evidence “Dedicated to securing the networks society depends on.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 10 | 69 contacts → | ||||
Partial evidence “With a heritage of creating National Cyber Security Centre certified products, Becrypt, a Leonardo company, is a trusted provider of endpoint cybersecurity software solutions.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 11 | 66 contacts → | ||||
Indirect evidence “We help businesses and individuals stay protected in an increasingly complex digital world.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 12 | 59 contacts → | ||||
Indirect evidence “Garrison is a London-based cybersecurity company founded in 2014 by David Garfield (CEO) and Henry Harrison (Chief Scientist).” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 13 | 52 contacts → | ||||
Indirect evidence “We are Adarma, independent leaders in detection and response services.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 14 | 41 contacts → | ||||
Partial evidence “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.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 15 | 38 contacts → | ||||
Partial evidence “Omerta - A Global Security Technology and Services Company.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 16 | 37 contacts → | ||||
Indirect evidence “Syxsense is the leading provider of innovative, intuitive technology that sees all and knows everything about every endpoint, in every location, everywhere inside and outside the…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 17 | 32 contacts → | ||||
Partial evidence “Defense.com is transforming the way businesses manage cyber security by allowing them to easily identify, prioritise and remediate threats.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 18 | 31 contacts → | ||||
Indirect evidence “At Acumen, our purpose is clear: we protect modern businesses from the complexities of cyber threats 24/7.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 19 | 31 contacts → | ||||
Partial evidence “A UK based organisation protecting organisations from cyber attacks with our CREST certified 24x7 UK SOC and offensive security services.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 20 | 27 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 Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 21 | 25 contacts → | ||||
Partial evidence “Encode is now part of Obrela Security Industries collectively delivering cutting edge Cyber Security Services, empowering organizations to better protect against cyber threats.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 22 | 23 contacts → | ||||
Partial evidence “AMR CyberSecurity delivers next generation cyber security services to assist organisations across a wide variety of sectors in understanding potential threats and effectively…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 23 | 19 contacts → | ||||
Indirect evidence “Why Clearswift?” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 24 | 17 contacts → | ||||
Indirect evidence “Infosec K2K safeguards your organisation’s most valuable assets with tailored cybersecurity solutions.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 25 | 17 contacts → | ||||
Partial evidence “We are a London based specialist supplier of cyber defence solution and information security services.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
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: computer security 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 computer security companies.
- Partial evidence
- Its own public description names part of computer security companies, so it works in or next to the category without describing itself that way.
- Indirect evidence
- The description shown does not name computer security 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 310 computer security companies based in the United Kingdom
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Computer security companies based in the United Kingdom at a glance
As of Aug 31, 2026Companies by employee count
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 computer security 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 “computer security 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 computer security 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 computer security 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, 4,089 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 August 31, 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.
Computer security companies by metro
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 computer security 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 computer security companies are there based in the United Kingdom?
RevenueBase identified 310 computer security companies headquartered in the United Kingdom as of August 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?
Sophos, headquartered in Abingdon, tops this list with the largest team on record.
Which city has the most computer security companies?
London leads with 119 headquartered companies, followed by Manchester (9) and Birmingham (5).
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 4,089 verified decision-maker contacts tracked across these 310 companies.
How current is this list?
The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on August 31, 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.
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