Company lists · Data verified August 2026

Top 25 Cybersecurity and defense software companies based in the United Kingdom

Name: Cybersecurity and defense software companies 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 435 companies tracked

There are 435 cybersecurity and defense software companies headquartered in the United Kingdom (RevenueBase, August 2026). RevenueBase tracks 13,985 professional contacts across them, including 6,069 with verified work emails and 1,773 with mobile numbers. London is the largest hub.

This list covers cybersecurity and defense software 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. Data current as of August 28, 2026.

435Companies

13,985Contacts tracked

6,069Verified emails

1,773Mobile numbers

Unlock all 435 companies Free account · no credit card · 2 minutes

The 25 largest cybersecurity and defense software companies based in the United Kingdom

Ranked by team size

Top 25 of 435 cybersecurity and defense software companies 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	SISA	Leicester	201-500	739	253
3	ROKE	Manchester	1,001-5,000	684	410
4	Enea AB	Belfast	501-1,000	638	208
5	Everfox	London	1,001-5,000	635	13
6	MASS	Lincoln	201-500	633	203
7	Withsecure	London	501-1,000	614	329
8	Bridewell	Edinburgh	201-500	304	189
9	Quorum Cyber	Edinburgh	201-500	292	177
10	Exclusive Networks UK	Mansfield	201-500	168	118
11	Cyberfort	Thatcham	51-200	160	88
12	Cipher سايڤر	London	201-500	135	50
13	Khipu Networks	Fleet	51-200	129	94
14	Foresite Cybersecurity	Farnborough	51-200	100	67
15	Drawbridge	London	51-200	97	60
16	Marss Group	London	51-200	96	59
17	Titania LTD	London	51-200	89	47
18	Cybersmart	London	51-200	83	55
19	Cryptomathic	London	51-200	77	46
20	Becrypt	London	51-200	69	56
21	Eset UK	Bournemouth	51-200	66	41
22	Allied Associates International	London	51-200	60	32
23	Garrison NOW A Part Of Everfox	London	51-200	59	2
24	Hexegic	London	51-200	52	30
25	Adarma Security	Edinburgh	201-500	52	23

Showing 25 of 435 cybersecurity and defense software companies based in the United Kingdom

See the full list, filter by size, metro and specialty, and get verified emails and direct dials for all 6,069 reachable decision-makers.

Free account · no credit card

See all 435 companies

Cybersecurity and defense software companies based in the United Kingdom at a glance

As of Aug 28, 2026

1-10Median size (employees)

LondonLargest hub · 188 HQs

1,773Contacts with mobile numbers

13Emails re-verified in last 30 days

Companies by employee count

1-10

217

11-50

139

51-200

201-500

501-1,000

1,001-5,000

5,001-10,000

Cybersecurity and defense software companies by metro

Metro	Companies
Cybersecurity and defense software companies in London	188
Cybersecurity and defense software companies in Manchester	18
Cybersecurity and defense software companies in Birmingham	9
Cybersecurity and defense software companies in Edinburgh	8
Cybersecurity and defense software companies in Cheltenham	7
Cybersecurity and defense software companies in Leicester	5
Cybersecurity and defense software companies in Glasgow	5

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 and defense software companies”, 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; 13 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 and defense software companies are there based in the United Kingdom?

There are 435 cybersecurity and defense software companies 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 and defense software companies?

London leads with 188 headquartered companies, followed by Manchester (18) and Birmingham (9).

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 6,069 verified decision-maker contacts tracked across these 435 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.

Ready to reach these companies? Verified emails and direct dials for all 435 cybersecurity and defense software companies based in the United Kingdom. Start with a free account, no credit card.

Get the full list

Related lists

Cybersecurity and defense software companies by geography

Browse the directory

Browse: Companies home · All United Kingdom lists · All Cybersecurity and defense software companies lists · New lists

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.