Company lists · Data verified August 2026

Top 25 Application security companies based in the United Kingdom

Name: Application security 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 144 companies tracked

There are 144 application security companies headquartered in the United Kingdom (RevenueBase, August 2026). RevenueBase tracks 1,706 professional contacts across them, including 548 with verified work emails and 141 with mobile numbers. London is the largest hub.

This list covers application 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. Data current as of August 28, 2026.

144Companies

1,706Contacts tracked

548Verified emails

141Mobile numbers

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The 25 largest application security companies based in the United Kingdom

Ranked by team size

Top 25 of 144 application security 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	Portswigger	Knutsford	51-200	261	89
2	Greenbone AG	London	51-200	108	28
3	Appcheck LTD	Leeds	51-200	97	64
4	Titania LTD	London	51-200	89	47
5	Ldra Limited	Wirral	51-200	86	40
6	Intruder	London	51-200	61	35
7	Secureflag	London	51-200	55	34
8	Riversafe	London	11-50	55	1
9	Coretech Security	Cheltenham	51-200	41	7
10	Secarma LTD	Manchester	11-50	34	23
11	defense.com	Stevenage	51-200	32	13
12	snapsec.co	London	1-10	30	6
13	Equixly	London	11-50	28	21
14	LICEL	London	11-50	28	17
15	Audacix Makers Of Cyber Chief & Qsome	London	11-50	20	3
16	Halo I.S	Leeds	11-50	19	9
17	Trustify LTD	London	11-50	17	13
18	CST Limited Computer Security Technology	London	11-50	17	2
19	Blackout Technologies	London	11-50	15	6
20	Eh1-Infotech Cybersecurity	London	11-50	15	1
21	Vulnhero	London	1-10	15	1
22	Mobius Binary	Bath	11-50	10	5
23	Equilibrium Security	Birmingham	11-50	9	5
24	CYTIX	Manchester	11-50	8	6
25	Corrata	London	11-50	8	3

Showing 25 of 144 application security companies based in the United Kingdom

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Application security companies based in the United Kingdom at a glance

As of Aug 28, 2026

1-10Median size (employees)

LondonLargest hub · 66 HQs

141Contacts with mobile numbers

5Emails re-verified in last 30 days

Companies by employee count

1-10

11-50

51-200

Application security companies by metro

Metro	Companies
Application security companies in London	66
Application security companies in Leeds	6
Application security companies in Manchester	6
Application security companies in Birmingham	4
Application security companies in Edinburgh	3
Application security companies in Oxford	3
Application security companies in Reading	2

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 “application security 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; 5 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 application security companies are there based in the United Kingdom?

There are 144 application security companies headquartered in the United Kingdom as of August 2026 (RevenueBase).

What is the largest company on this list?

Portswigger, headquartered in Knutsford, tops this list with the largest team on record.

Which city has the most application security companies?

London leads with 66 headquartered companies, followed by Leeds (6) and Manchester (6).

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 548 verified decision-maker contacts tracked across these 144 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.