Company lists · Data refreshed August 2026
Top 25 Api security companies based in the United Kingdom
RevenueBase identified 382 api security companies headquartered in the United Kingdom as of August 2026 and 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. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed August 31, 2026.
Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, 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.
The 25 largest api security companies based in the United Kingdom
Ranked by team size| # | Company | Contacts | |||
|---|---|---|---|---|---|
| 1 | 739 contacts → | ||||
Partial evidence “SISA is a global forensics-driven cybersecurity solutions company, trusted by leading organizations for securing their businesses with robust preventive, detective, and corrective…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 2 | 160 contacts → | ||||
Partial evidence “At Cyberfort we are passionate about the cyber security services we deliver for our customers which keeps their people, data, systems and technology infrastructure secure…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 3 | 118 contacts → | ||||
Indirect evidence “Bulletproof is now part of WorkNest Secure.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 4 | 100 contacts → | ||||
Indirect evidence “As the world becomes more connected, our lives and businesses are more vulnerable.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 5 | 80 contacts → | ||||
Indirect evidence “At Reliance Cyber, we believe in truly partnering with our customers.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 6 | 56 contacts → | ||||
Partial evidence “CyberLab is the UK-leading cyber security consultancy and managed services provider, trusted by over 1,200 enterprise businesses, government departments, and household names to…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 7 | 52 contacts → | ||||
Indirect evidence “At Hexegic we are not just passionate about protecting data through our Cyber services we are passionate about helping companies release the potential of the data they hold…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 8 | 52 contacts → | ||||
Indirect evidence “We are Adarma, independent leaders in detection and response services.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 9 | 41 contacts → | ||||
Partial evidence “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.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 10 | 34 contacts → | ||||
Indirect evidence “Secarma exists to keep the world safe.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 11 | 32 contacts → | ||||
Partial evidence “Defense.com is transforming the way businesses manage cyber security by allowing them to easily identify, prioritise and remediate threats.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 12 | 32 contacts → | ||||
Partial evidence “Aristi is a specialist provider of cyber security services with over 17 years of experience.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 13 | 30 contacts → | ||||
Partial evidence “Cyber security can feel overwhelming.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 14 | 25 contacts → | ||||
Partial evidence “Encode is now part of Obrela Security Industries collectively delivering cutting edge Cyber Security Services, empowering organizations to better protect against cyber threats.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 15 | 24 contacts → | ||||
Partial evidence “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…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 16 | 24 contacts → | ||||
Indirect evidence “Redfox Cybersecurity is a fast-growing cybersecurity consulting firm, spread across 4 countries.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 17 | 24 contacts → | ||||
Partial evidence “SSL247 (A Sectigo Company) has nearly 20 years of security consulting experience operating in 18 different markets globally.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 18 | 20 contacts → | ||||
Partial evidence “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…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 19 | 19 contacts → | ||||
Partial evidence “th4ts3cur1ty.company supplies cyber security services internationally.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 20 | 19 contacts → | ||||
Indirect evidence “Halo I.S is not just another cybersecurity organization based in the UK; we're a testament to evolution and client-centric innovation.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 21 | 17 contacts → | ||||
Partial evidence “We are a London based specialist supplier of cyber defence solution and information security services.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 22 | 16 contacts → | ||||
Indirect evidence “B10SEC is a company specialising in cybersecurity and data protection services and solutions, headquartered in Gloucestershire, UK, with branches in Portugal, Brazil and Mexico.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 23 | 15 contacts → | ||||
Partial evidence “Best penetration testing service - Teiss Awards 2024 Managed cloud service winner - Stratus Awards 2023 Security vendor of the year - Computing security excellence awards 2023…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 24 | 15 contacts → | ||||
Indirect evidence “is an ISO 9001:2015 and ISO/IEC 27001:2022 certified, DPIIT-recognized cybersecurity company delivering structured External Vulnerability Assessment & Penetration Testing (VAPT)…” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
| 25 | 14 contacts → | ||||
Indirect evidence “Who We Are DataSixth delivers Cybersecurity Intelligence.” Source: RevenueBase Database · checked Aug 31, 2026Thanks. The Data Team will review it. | |||||
RevenueBase Smart Search
RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: api security companies. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.
- Strong evidence
- The company's own public description of its business names api security companies.
- Partial evidence
- Its own public description names part of api security companies, so it works in or next to the category without describing itself that way.
- Indirect evidence
- The description shown does not name api security companies. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.
RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.
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 31, 2026Companies by employee count
How this list was built
Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among api security companies, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.
- Source
- The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
- What qualifies
- Companies headquartered in the United Kingdom whose own description of what they do matches “api security companies”. Matching reads each company's description, not its industry code or its name.
- RevenueBase Smart Search
- RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names api security companies), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
- What we exclude
- Companies whose own description does not clearly place them among api security companies, and records with no verified work email. Companies headquartered outside United Kingdom are excluded even when they keep an office there.
- Match quality
- In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
- 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 listed company carries at least one verified work email, 1,231 across the full list. 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 August 31, 2026. Lists refresh periodically as the graph is re-checked.
- Corrections
- Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.
Api security companies by metro
Frequently asked
What is RevenueBase Smart Search?
RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names api security companies, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.
How many api security companies are there based in the United Kingdom?
RevenueBase identified 382 api security companies headquartered in the United Kingdom as of August 2026, matched on each company's own description of what it does rather than its industry code.
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 refreshes periodically as the company graph is re-checked. This page's figures were pulled on August 31, 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 Smart Search, 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.
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