Company lists · Data verified August 2026

Top 25 Api security companies based in the United Kingdom

Name: Api 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 382 companies tracked

There are 382 api security companies headquartered in the United Kingdom (RevenueBase, August 2026). RevenueBase tracks 4,477 professional contacts across them, including 1,231 with verified work emails and 338 with mobile numbers. London is the largest hub.

This list covers api 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.

382Companies

4,477Contacts tracked

1,231Verified emails

338Mobile numbers

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The 25 largest api security companies based in the United Kingdom

Ranked by team size

Top 25 of 382 api 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	Bulletproof Cyber Security	London	51-200	118	75
4	Foresite Cybersecurity	Farnborough	51-200	100	67
5	Reliance Cyber	Waterloo	51-200	80	47
6	Cyberlab	Lincoln	51-200	56	41
7	Hexegic	London	51-200	52	30
8	Adarma Security	Edinburgh	201-500	52	23
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	Aristi	Birmingham	11-50	32	10
13	Citation Cyber	Bailrigg	11-50	30	11
14	Encode	London	51-200	25	9
15	Pentesec	Peterborough	51-200	24	18
16	Redfox Cybersecurity	London	11-50	24	6
17	Ssl247 A Sectigo Company	London	51-200	24	1
18	Secure Purple	London	11-50	20	2
19	th4ts3cur1ty.company	London	11-50	19	13
20	Halo I.S	Leeds	11-50	19	9
21	CST Limited Computer Security Technology	London	11-50	17	2
22	B10sec	Cheltenham	11-50	16	6
23	Lrqa Nettitude	Birmingham	201-500	15	14
24	Eh1-Infotech Cybersecurity	London	11-50	15	1
25	Datasixth Consulting	London	51-200	14	7

Showing 25 of 382 api security companies based in the United Kingdom

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Api security companies based in the United Kingdom at a glance

As of Aug 28, 2026

1-10Median size (employees)

LondonLargest hub · 160 HQs

338Contacts with mobile numbers

2Emails re-verified in last 30 days

Companies by employee count

1-10

223

11-50

124

51-200

201-500

501-1,000

1,001-5,000

Api security companies by metro

Metro	Companies
Api security companies in London	160
Api security companies in Manchester	18
Api security companies in Cheltenham	12
Api security companies in Birmingham	10
Api security companies in Milton Keynes	5
Api security companies in Edinburgh	5
Api security companies in Cambridge	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 “api 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 api security companies are there based in the United Kingdom?

There are 382 api 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 api security companies?

London leads with 160 headquartered companies, followed by Manchester (18) and Cheltenham (12).

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 1,231 verified decision-maker contacts tracked across these 382 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.