Company lists · Data refreshed September 2026

Top 25 Api security firms based in the United Kingdom

RevenueBase identified 271 company matches for api security firms associated with the United Kingdom as of September 2026 and tracks 2,999 professional contacts across them, including 665 with verified work emails. London is the largest hub.

This list covers company matches for api security firms associated with the United Kingdom, found by RevenueBase SmartSearch using the meaning of business descriptions in its company graph at Exact. Ranked by professionals tracked, largest first. Rows show recorded descriptions where available, Exact search membership and the snapshot date. Data refreshed September 27, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase SmartSearch, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list RevenueBase SmartSearch · Exact Recorded Sep 27, 2026 How this list was built
271Companies
2,999Contacts tracked
665Verified emails
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The 25 largest api security firms based in the United Kingdom

Ranked by team size
Top 25 of 271 company matches for api security firms based in the United Kingdom, ordered by professional contacts tracked in RevenueBase, largest first. Recorded Sep 27, 2026. The RevenueBase SmartSearch column shows Exact match membership in this saved search. Click a contact count to view that company's people. Totals use company locations recorded by RevenueBase; the displayed preview is a smaller selection.
#CompanyRevenueBase SmartSearchHeadquartersEmployeesContacts
1Exact matchWaterloo, United KingdomHQ recorded Sep 27, 202651-20080 contacts →

Exact match

“At Reliance Cyber, we believe in truly partnering with our customers.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
2Exact matchOxford, United KingdomHQ recorded Sep 27, 202651-20073 contacts →

Exact match

“Dionach by Nomios has over 25 years of expertise in information security, supporting organisations in building resilience against ever‑evolving cyber threats.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
3Exact matchLondon, United KingdomHQ recorded Sep 27, 202611-5057 contacts →

Exact match

“We deliver services in Cybersecurity, Application Security and DevOps and are trusted by some of the world’s leading brands to maximise the value of their security investments and…”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
4Exact matchEdinburgh, United KingdomHQ recorded Sep 27, 2026201-50051 contacts →

Exact match

“We are Adarma, independent leaders in detection and response services.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
5Exact matchCheltenham, United KingdomHQ recorded Sep 27, 202651-20042 contacts →

Exact match

“CoreTech is a specialist cyber security company whose people are motivated by the desire to deliver exceptional capabilities coupled with a real sense of mission.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
6Exact matchCirencester, United KingdomHQ recorded Sep 27, 202611-5039 contacts →

Exact match

“We help organisations understand, optimise, and strengthen their cybersecurity.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
7Exact matchManchester, United KingdomHQ recorded Sep 27, 202611-5036 contacts →

Exact match

“Secarma exists to keep the world safe.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
8Exact matchCrawley, United KingdomHQ recorded Sep 27, 202611-5035 contacts →

Exact match

“ERGOS is an award-winning IT Managed Service Provider.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
9Exact matchCambridge, United KingdomHQ recorded Sep 27, 202611-5034 contacts →

Exact match

“Pentesting Exams by Pentesting Experts.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
10Exact matchStevenage, United KingdomHQ recorded Sep 27, 202651-20032 contacts →

Exact match

“Defense.com is transforming the way businesses manage cyber security by allowing them to easily identify, prioritise and remediate threats.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
11Exact matchBirmingham, United KingdomHQ recorded Sep 27, 202611-5032 contacts →

Exact match

“Aristi is a specialist provider of cyber security services with over 17 years of experience.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
12Exact matchLancaster, United KingdomHQ recorded Sep 27, 202611-5030 contacts →

Exact match

“Cyber security can feel overwhelming.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
13Exact matchPortsmouth, United KingdomHQ recorded Sep 27, 202611-5029 contacts →

Exact match

“Imagine a world where cyber threats are simply another challenge that you're fully equipped to handle.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
14Exact matchAltrincham, United KingdomHQ recorded Sep 27, 202611-5026 contacts →

Exact match

“Based in Manchester UK, we are an independent Cyber Security Consultancy providing Security services across a wide range of markets, from multi-national Corporate Organisations…”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
15Exact matchLondon, United KingdomHQ recorded Sep 27, 202651-20025 contacts →

Exact match

“Encode is now part of Obrela Security Industries collectively delivering cutting edge Cyber Security Services, empowering organizations to better protect against cyber threats.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
16Exact matchLondon, United KingdomHQ recorded Sep 27, 202651-20024 contacts →

Exact match

“SSL247 (A Sectigo Company) has nearly 20 years of security consulting experience operating in 18 different markets globally.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
17Exact matchNewbury, United KingdomHQ recorded Sep 27, 202611-5023 contacts →

Exact match

“CyberCrowd are a market leader in the cyber security realm, offering everything from Assessment Services through to Pen Testing, CISOaaS, Certification Readiness, DPO services…”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
18Exact matchPeterborough, United KingdomHQ recorded Sep 27, 202651-20023 contacts →

Exact match

“Check Point Partner of the Year 2022 CRN MSSP of the Year 2021 Pentesec has been challenging the status quo in Cyber Security since 2014 when 5 industry veterans decided they were…”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
19Exact matchLondon, United KingdomHQ recorded Sep 27, 202611-5023 contacts →

Exact match

“Toro was founded on creating the UK's first Red Team penetration test - and then attacking hundreds of clients by hacking their systems, influencing / social engineering staff and…”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
20Exact matchCambridge, United KingdomHQ recorded Sep 27, 202611-5021 contacts →

Exact match

“Chaleit is a cyber security management consultancy that aligns business context with real-world capability to solve complex risks.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
21Exact matchLondon, United KingdomHQ recorded Sep 27, 202611-5020 contacts →

Exact match

“Secure Purple is a leading cyber security and digital safety firm that provides innovative solutions and services to help organisations and individuals stay protected in the…”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
22Exact matchLeeds, United KingdomHQ recorded Sep 27, 202611-5019 contacts →

Exact match

“Halo I.S is not just another cybersecurity organization based in the UK; we're a testament to evolution and client-centric innovation.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
23Exact matchLondon, United KingdomHQ recorded Sep 27, 202611-5018 contacts →

Exact match

“th4ts3cur1ty.company supplies cyber security services internationally.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
24Exact matchLondon, United KingdomHQ recorded Sep 27, 202611-5017 contacts →

Exact match

“We are a leading cybersecurity services organization with more than a decade of proven expertise in consulting, solution implementation and managed services.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
25Exact matchLondon, United KingdomHQ recorded Sep 27, 202611-5017 contacts →

Exact match

“We are a London based specialist supplier of cyber defence solution and information security services.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase

Showing 25 of 271 api security firms based in the United Kingdom

See the full list, filter by size, metro and specialty, and access 665 tracked professional contacts with verified work emails. Direct dials are available where recorded.

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Api security firms based in the United Kingdom at a glance

As of Sep 27, 2026
22.2%Verified-email coverage
11.1Average contacts per company
1-10Median size (employees)
38.7%Largest-city concentration · London
Sep 27, 2026Page data refreshed

Companies by employee count

1-10
159
11-50
88
51-200
17
201-500
4
501-1,000
2
1,001-5,000
1

Email recency for this list is measured worldwide rather than for United Kingdom, so it is reported there. Company counts and contact totals on this page are exact for United Kingdom, over 271 companies.

How this list was built

The recorded descriptions help you assess these company matches. Check a company’s website for its current services and locations.

Source
The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase SmartSearch, the natural-language company search available to every RevenueBase user.
What qualifies
Company records associated with the United Kingdom whose business descriptions match “api security firms” by meaning at the Exact setting. Descriptions are compiled in the RevenueBase company graph from public websites, profiles and company information where available; they are not guaranteed quotations from the company's website.
RevenueBase SmartSearch
Describe a niche company in your own words to find businesses by meaning. Exact, Similar, Related and Broad control the breadth of RevenueBase SmartSearch. This saved list uses Exact. Each row's Exact match badge shows inclusion in that search, not an individual score or a service-quality judgment.
Public preview
The public preview omits records without a verified work email. Where headquarters information is recorded, preview rows are also filtered to this page’s location. Dataset totals and geographic summaries describe the full matched records before these preview filters.
Match quality
RevenueBase's August 25, 2026 study assessed 4,198 description/company pairs across matching settings. The publisher reports 86% good or better at Exact. This evaluates the method across queries; it does not audit this individual list. Recorded company descriptions, where available, help you judge each match yourself. Read the full methodology: how the lists are built and what the study measures.
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
Every displayed company carries at least one verified work email. RevenueBase tracks 665 professional contacts with verified work emails across the full matched dataset. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh
This page's figures were pulled from the company graph on September 27, 2026. Lists refresh periodically as the graph is re-checked.
Record context
Company records and descriptions can change. Check the company's website for its current services and locations.

Frequently asked

What is RevenueBase SmartSearch?

RevenueBase SmartSearch finds niche companies by the meaning of their business descriptions in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit your description. This list uses Exact for “api security firms”; each Exact match badge shows search membership, not an individual similarity or quality score.

How many api security firms are there based in the United Kingdom?

RevenueBase identified 271 company matches for api security firms associated with the United Kingdom as of September 2026, using the meaning of business descriptions at Exact. This is the recorded matched set in the RevenueBase company graph.

What is the largest company on this list?

Reliance Cyber tops the displayed preview by professional contacts tracked in RevenueBase. Recorded headquarters appear in the company rows.

Which city has the most api security firms?

London leads with 105 company records, followed by Manchester (16) and Birmingham (8).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work limited free results with 500 credits to start. Upgrading provides access to the 665 professional contacts with verified work emails tracked across these 271 companies; direct dials are available where recorded.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 27, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 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 with RevenueBase SmartSearch, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.