Company lists · Data verified August 2026

Top 25 Data security companies based in the United Kingdom

Name: Data 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 277 companies tracked

There are 277 data security companies headquartered in the United Kingdom (RevenueBase, August 2026). RevenueBase tracks 3,800 professional contacts across them, including 958 with verified work emails and 305 with mobile numbers. London is the largest hub.

This list covers data 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.

277Companies

3,800Contacts tracked

958Verified emails

305Mobile numbers

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The 25 largest data security companies based in the United Kingdom

Ranked by team size

Top 25 of 277 data 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	SISA	Leicester	201-500	739	253
2	Cyberfort	Thatcham	51-200	160	88
3	Foresite Cybersecurity	Farnborough	51-200	100	67
4	Cryptomathic	London	51-200	77	46
5	Telesoft	Blandford	51-200	68	19
6	Eset UK	Bournemouth	51-200	66	41
7	Hexegic	London	51-200	52	30
8	Adarma Security	Edinburgh	201-500	52	23
9	Eticloud	Sheffield	51-200	46	17
10	MPCH	London	11-50	42	17
11	Galaxkey	St. Albans	51-200	38	29
12	defense.com	Stevenage	51-200	32	13
13	Istorage Limited	Greenford	11-50	31	18
14	Smartsafe Consulting And Technology	London	11-50	26	7
15	Encode	London	51-200	25	9
16	Pentesec	Peterborough	51-200	24	18
17	AMR Cybersecurity	Cheltenham	11-50	23	17
18	4secure LTD	Northampton	11-50	22	13
19	Clearswift	Berkshire	201-500	19	4
20	B10sec	Cheltenham	11-50	16	6
21	Bruce & Butler	Sheffield	11-50	15	10
22	Everycloud AI & Data Security	London	11-50	14	9
23	Netrascale	London	11-50	14	2
24	Praeferre	London	11-50	13	2
25	PC Power International LTD	London	11-50	10	8

Showing 25 of 277 data security companies based in the United Kingdom

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Data security companies based in the United Kingdom at a glance

As of Aug 28, 2026

1-10Median size (employees)

LondonLargest hub · 125 HQs

305Contacts with mobile numbers

2Emails re-verified in last 30 days

Companies by employee count

1-10

162

11-50

51-200

201-500

501-1,000

5,001-10,000

Data security companies by metro

Metro	Companies
Data security companies in London	125
Data security companies in Manchester	10
Data security companies in Sheffield	5
Data security companies in Cheltenham	5
Data security companies in Leicester	4
Data security companies in Birmingham	3
Data security companies in Oxford	3

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 “data 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; 2 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 data security companies are there based in the United Kingdom?

There are 277 data security companies headquartered in the United Kingdom as of August 2026 (RevenueBase).

What is the largest company on this list?

SISA, headquartered in Leicester, tops this list with the largest team on record.

Which city has the most data security companies?

London leads with 125 headquartered companies, followed by Manchester (10) and Sheffield (5).

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 958 verified decision-maker contacts tracked across these 277 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.