Company lists · Data verified August 2026

Top 25 Cybersecurity startups based in the United Kingdom

Name: Cybersecurity startups 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 1,362 companies tracked

There are 1,362 cybersecurity startups headquartered in the United Kingdom (RevenueBase, August 2026). RevenueBase tracks 28,622 professional contacts across them, including 12,476 with verified work emails and 4,497 with mobile numbers. London is the largest hub.

This list covers cybersecurity startups 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.

1,362Companies

28,622Contacts tracked

12,476Verified emails

4,497Mobile numbers

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The 25 largest cybersecurity startups based in the United Kingdom

Ranked by team size

Top 25 of 1,362 cybersecurity startups 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	Zerofox	n/a	501-1,000	894	382
5	SISA	Leicester	201-500	739	253
6	Claroty	London	501-1,000	729	152
7	Everfox	London	1,001-5,000	635	13
8	Withsecure	London	501-1,000	614	329
9	Lodge Security	Cirencester	1,001-5,000	419	62
10	Bridewell	Edinburgh	201-500	304	189
11	Quorum Cyber	Edinburgh	201-500	292	177
12	QODEA	London	201-500	237	35
13	The Redesign Group	London	201-500	201	140
14	Intragen	London	201-500	188	128
15	Exclusive Networks UK	Mansfield	201-500	168	118
16	Cyberfort	Thatcham	51-200	160	88
17	Cybersec Consulting	London	201-500	141	76
18	Cipher سايڤر	London	201-500	135	50
19	Instil	Belfast	51-200	120	78
20	Bulletproof Cyber Security	London	51-200	118	75
21	Foresite Cybersecurity	Farnborough	51-200	100	67
22	Drawbridge	London	51-200	97	60
23	Caretower An Integrity360 Company	London	201-500	97	12
24	Nomios Uk&i	Manchester	51-200	96	49
25	Cyberone	London	51-200	96	39

Showing 25 of 1,362 cybersecurity startups based in the United Kingdom

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Cybersecurity startups based in the United Kingdom at a glance

As of Aug 28, 2026

1-10Median size (employees)

LondonLargest hub · 586 HQs

4,497Contacts with mobile numbers

18Emails re-verified in last 30 days

Companies by employee count

1-10

808

11-50

398

51-200

109

201-500

501-1,000

1,001-5,000

5,001-10,000

Cybersecurity startups by metro

Metro	Companies
Cybersecurity startups in London	586
Cybersecurity startups in Manchester	56
Cybersecurity startups in Cheltenham	23
Cybersecurity startups in Birmingham	21
Cybersecurity startups in Cambridge	18
Cybersecurity startups in Edinburgh	13
Cybersecurity startups in Leeds	13

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 startups”, 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; 18 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 startups are there based in the United Kingdom?

There are 1,362 cybersecurity startups 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 startups?

London leads with 586 headquartered companies, followed by Manchester (56) and Cheltenham (23).

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 12,476 verified decision-maker contacts tracked across these 1,362 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.