Company lists · Data verified August 2026

Top 25 Cybersecurity firms based in the United Kingdom

Name: Cybersecurity firms based in the United Kingdom
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Verified Aug 28, 2026 2,100 companies tracked

There are 2,100 cybersecurity firms headquartered in the United Kingdom (RevenueBase, August 2026). RevenueBase tracks 40,405 professional contacts across them, including 16,845 with verified work emails and 5,377 with mobile numbers. London is the largest hub.

This list covers cybersecurity firms headquartered in the United Kingdom, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Data current as of August 28, 2026.

2,100Companies

40,405Contacts tracked

16,845Verified emails

5,377Mobile numbers

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The 25 largest cybersecurity firms based in the United Kingdom

Ranked by team size

Top 25 of 2,100 cybersecurity firms based in the United Kingdom, ranked by team size, largest first. Data verified Aug 28, 2026. Click a count to unlock that company's people.
#	Company	HQ	Employees	Contacts	Verified emails
1	Sophos	Abingdon	5,001-10,000	4,963	2,711
2	Sailpoint	London	1,001-5,000	3,059	1,979
3	Darktrace	Cambridge	1,001-5,000	2,590	1,791
4	Hack The BOX	Folkestone	n/a	1,946	21
5	Zerofox	n/a	501-1,000	894	382
6	SISA	Leicester	201-500	739	253
7	Claroty	London	501-1,000	729	152
8	ROKE	Manchester	1,001-5,000	684	410
9	Everfox	London	1,001-5,000	635	13
10	MASS	Lincoln	201-500	633	203
11	Withsecure	London	501-1,000	614	329
12	Yubico	West Horsley	501-1,000	546	370
13	Biocatch	London	201-500	429	316
14	Integrity360	London	501-1,000	341	199
15	Bridewell	Edinburgh	201-500	304	189
16	Quorum Cyber	Edinburgh	201-500	292	177
17	Vipre Security Group	Newcastle	201-500	207	117
18	Netcraft	London	201-500	206	105
19	The Redesign Group	London	201-500	201	140
20	Intragen	London	201-500	188	128
21	Exclusive Networks UK	Mansfield	201-500	168	118
22	LOGIQ	Bristol	201-500	142	81
23	Cybersec Consulting	London	201-500	141	76
24	Cipher سايڤر	London	201-500	135	50
25	Egress, A Knowbe4 Company	London	201-500	123	85

Showing 25 of 2,100 cybersecurity firms based in the United Kingdom

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Cybersecurity firms based in the United Kingdom at a glance

As of Aug 28, 2026

1-10Median size (employees)

LondonLargest hub · 891 HQs

5,377Contacts with mobile numbers

28Emails re-verified in last 30 days

Companies by employee count

1-10

1,267

11-50

592

51-200

166

201-500

501-1,000

1,001-5,000

5,001-10,000

Cybersecurity firms by metro

Metro	Companies
Cybersecurity firms in London	891
Cybersecurity firms in Manchester	74
Cybersecurity firms in Birmingham	36
Cybersecurity firms in Cheltenham	30
Cybersecurity firms in Cambridge	29
Cybersecurity firms in Bristol	24
Cybersecurity firms in Edinburgh	23

How this list was built

Source: The RevenueBase company graph: 21.3 million companies and 398.9 million professional contacts resolved from primary sources.
Inclusion: Companies whose own business descriptions match “cybersecurity firms”, with match quality audited by blind human judging, and headquartered in the United Kingdom.
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: Contact records re-verify on a rolling cadence; 28 contacts on this list were re-verified in the last 30 days.
Refresh: Lists are refreshed periodically as the underlying company graph is re-verified. Last verified Aug 28, 2026.

Frequently asked

How many cybersecurity firms are there based in the United Kingdom?

There are 2,100 cybersecurity firms headquartered in the United Kingdom as of August 2026 (RevenueBase).

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 cybersecurity firms?

London leads with 891 headquartered companies, followed by Manchester (74) and Birmingham (36).

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 16,845 verified decision-maker contacts tracked across these 2,100 companies.

How current is this list?

The list is refreshed periodically as the underlying company graph is re-verified. It was last verified on August 28, 2026.

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About this data

RevenueBase is a B2B contact data platform. Its company graph covers 21.3 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, the same data that powers RevenueBase's B2B data products and the free research portal.