Company lists · Data verified August 2026

Top 25 Cybersecurity companies based in London, United Kingdom

Name: Cybersecurity companies based in London, United Kingdom
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Verified Aug 28, 2026 876 companies tracked

Our directory lists 876 cybersecurity companies based in London, United Kingdom, with 23,177 professional contacts and 6,885 email addresses. The list was last updated in August 2026, and London is the single most-represented city among the companies listed.

Cybersecurity companies provide products and services that protect systems, networks, applications, devices, and data from unauthorized access, disruption, or misuse. This list covers companies that provide cybersecurity products, services, consulting, assessments, monitoring, incident response, or related protection for digital systems and data. Ranked by team size, largest first. Data current as of August 28, 2026.

876Companies

23,177Contacts tracked

6,885Verified emails

3,190Mobile numbers

Unlock all 876 companies Free account · no credit card · 2 minutes

The 25 largest cybersecurity companies based in London, United Kingdom

Ranked by team size

Top 25 of 876 cybersecurity companies based in London, 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	Hackerone	London	n/a	5,938	402
2	Sailpoint	London	1,001-5,000	3,059	1,979
3	Netwrix Corporation	London	501-1,000	799	550
4	Claroty	London	501-1,000	729	152
5	Everfox	London	1,001-5,000	635	13
6	Withsecure	London	501-1,000	614	329
7	Integrity360	London	501-1,000	341	199
8	Netcraft	London	201-500	206	105
9	The Redesign Group	London	201-500	201	140
10	Intragen	London	201-500	188	128
11	Gorilla Technology Group	London	51-200	188	75
12	Risk Associates - Emea & Asia	London	51-200	169	62
13	Cybersec Consulting	London	201-500	141	76
14	Cipher سايڤر	London	201-500	135	50
15	Egress, A Knowbe4 Company	London	201-500	123	85
16	Cybersrc Consultancy	London	51-200	99	39
17	Drawbridge	London	51-200	97	60
18	Cyberone	London	51-200	96	39
19	Glasswall	London	51-200	90	47
20	Titania LTD	London	51-200	89	47
21	Wavenet Cyberguard	London	201-500	86	58
22	Cybanetix	London	51-200	78	45
23	Becrypt	London	51-200	69	56
24	Smartnumbers	London	51-200	68	40
25	Cyro Cyber	London	51-200	63	10

Showing 25 of 876 cybersecurity companies based in London, United Kingdom

See the full list, filter by size, metro and specialty, and get verified emails and direct dials for all 6,885 reachable decision-makers.

Free account · no credit card

See all 876 companies

Cybersecurity companies based in London, United Kingdom at a glance

As of Aug 28, 2026

1-10Median size (employees)

LondonLargest hub · 876 HQs

3,190Contacts with mobile numbers

42Emails re-verified in last 30 days

Companies by employee count

1-10

492

11-50

264

51-200

201-500

501-1,000

1,001-5,000

10001+

Cybersecurity companies by metro in the United Kingdom

Metro	Companies
Cybersecurity companies in London	876
Cybersecurity companies in Manchester	72
Cybersecurity companies in Birmingham	34
Cybersecurity companies in Cheltenham	31
Cybersecurity companies in Cambridge	28
Cybersecurity companies in Leeds	22
Cybersecurity companies in Bristol	21

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 companies”, with match quality audited by blind human judging, and headquartered in London, 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; 42 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 companies are in the directory?

The directory lists 876 cybersecurity companies based in London, United Kingdom.

Which city has the most cybersecurity companies?

London is the single most-represented city among the cybersecurity companies on the list.

How many contacts are available for cybersecurity companies?

The directory includes 23,177 professional contacts and 6,885 email addresses for the listed cybersecurity companies.

Ready to reach these companies? Verified emails and direct dials for all 876 cybersecurity companies based in London, United Kingdom. Start with a free account, no credit card.

Get the full list

Related lists

Cybersecurity companies by geography

Browse the directory

Browse: Companies home · Cybersecurity companies in United Kingdom · All United Kingdom lists · All Cybersecurity 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.