Company lists · Data refreshed September 2026

Top 25 Api security testing firms based in the United Kingdom

RevenueBase identified 144 company matches for api security testing firms associated with the United Kingdom as of September 2026 and tracks 882 professional contacts across them, including 384 with verified work emails. London is the largest hub.

This list covers company matches for api security testing 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
144Companies
882Contacts tracked
384Verified emails
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The 25 largest api security testing firms based in the United Kingdom

Ranked by team size
Top 25 of 144 company matches for api security testing 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 matchLeeds, United KingdomHQ recorded Sep 27, 202651-20099 contacts →

Exact match

“AppCheck is a Complete Enterprise Security Testing Solution that provides up to the minute vulnerability coverage for your entire estate.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
2Exact 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
3Exact 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
4Exact 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
5Exact 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
6Exact 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
7Exact 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
8Exact 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
9Exact 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
10Exact matchWimbledon, United KingdomHQ recorded Sep 27, 202611-5019 contacts →

Exact match

“We are dedicated to advancing cyber security through meticulous assessment of products and services engineered to detect and thwart cyber attacks.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
11Exact 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
12Exact matchLondon, United KingdomHQ recorded Sep 27, 202611-5015 contacts →

Exact match

“is an ISO 9001:2015 and ISO/IEC 27001:2022 certified, DPIIT-recognized cybersecurity company delivering structured External Vulnerability Assessment & Penetration Testing (VAPT)…”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
13Exact matchHolborn, United KingdomHQ recorded Sep 27, 20261-1013 contacts →

Exact match

“Laburity: Cyber Security Research and Services Company.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
14Exact matchMilton Keynes, United KingdomHQ recorded Sep 27, 202611-5012 contacts →

Exact match

“We offer specialist CREST & CHECK Approved Penetration Testing services in order to secure our clients most critical assets.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
15Exact matchBelfast, United KingdomHQ recorded Sep 27, 202611-5012 contacts →

Exact match

“Cyber Guarded is a vendor independent business which provides Cyber Security auditing and testing services.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
16Exact matchBath, United KingdomHQ recorded Sep 27, 202611-5011 contacts →

Exact match

“At Mobius Binary we care about your reputation and the loss that could result from violating your digital boundaries.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
17Exact matchLondon, United KingdomHQ recorded Sep 27, 202611-5010 contacts →

Exact match

“SecureTeam are a UK-based information security practice, specialising in all areas of cybersecurity.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
18Exact matchBirmingham, United KingdomHQ recorded Sep 27, 202611-509 contacts →

Exact match

“At Equilibrium Security, we’re a team of certified Cyber Security experts dedicated to keeping your business safe.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
19Exact matchManchester, United KingdomHQ recorded Sep 27, 202611-508 contacts →

Exact match

“Cytix is the AppSec layer that focuses testing where it matters.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
20Exact matchLeamington Spa, United KingdomHQ recorded Sep 27, 202611-508 contacts →

Exact match

“Building the best Cyber Security company you've never heard of.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
21Exact matchManchester, United KingdomHQ recorded Sep 27, 20261-107 contacts →

Exact match

“RM Information Security are a specialist penetration testing and information security consultancy based in the north of England.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
22Exact matchAylesbury, United KingdomHQ recorded Sep 27, 202611-507 contacts →

Exact match

“Kelltron Consulting Services is a globally recognized cybersecurity consulting firm with a strong presence in the United Kingdom, United States, and India.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
23Exact matchBirmingham, United KingdomHQ recorded Sep 27, 202611-506 contacts →

Exact match

“Cyndicate Labs are a UK based Cyber Security consultancy.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
24Exact matchLondon, United KingdomHQ recorded Sep 27, 20261-106 contacts →

Exact match

“Appsecco Inc.”

Recorded in the RevenueBase company graph · Sep 27, 2026 · View company records in RevenueBase
25Exact matchCranfield, United KingdomHQ recorded Sep 27, 202611-506 contacts →

Exact match

“Secure Debug: Your Full-Spectrum Cybersecurity Guardian!”

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

Showing 25 of 144 api security testing firms based in the United Kingdom

See the full list, filter by size, metro and specialty, and access 384 tracked professional contacts with verified work emails. Direct dials are available where recorded.

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Api security testing firms based in the United Kingdom at a glance

As of Sep 27, 2026
43.5%Verified-email coverage
6.1Average contacts per company
1-10Median size (employees)
34.7%Largest-city concentration · London
Sep 27, 2026Page data refreshed

Companies by employee count

1-10
92
11-50
45
51-200
2
201-500
2
501-1,000
1
1,001-5,000
1
5,001-10,000
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 144 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 testing 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 384 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 testing firms”; each Exact match badge shows search membership, not an individual similarity or quality score.

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

RevenueBase identified 144 company matches for api security testing 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?

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

Which city has the most api security testing firms?

London leads with 50 company records, followed by Manchester (7) and Birmingham (6).

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 384 professional contacts with verified work emails tracked across these 144 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.