Company lists · Data refreshed September 2026

Top 25 Cybersecurity startups based in the United Kingdom

Name: Cybersecurity startups based in the United Kingdom
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 1, 2026 1,362 companies tracked

RevenueBase identified 1,362 cybersecurity startups headquartered in the United Kingdom as of September 2026 and tracks 28,622 professional contacts across them, including 12,476 with verified work emails and 4,497 with mobile numbers. London is the largest hub.

This list covers cybersecurity startups 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 September 1, 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.

How to read this list RevenueBase Smart Search rating on every row Refreshed Sep 1, 2026 86% judged on-target in blind review

1,362Companies

28,622Contacts tracked

12,476Verified emails

4,497Mobile numbers

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The 25 largest cybersecurity startups based in the United Kingdom

Ranked by team size

Top 25 of 1,362 cybersecurity startups based in the United Kingdom, ranked by team size, largest first. Data refreshed Sep 1, 2026. RevenueBase Smart Search rates how each company's information relates to cybersecurity startups: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	Sophos	Partial evidence	Abingdon, United Kingdom	5,001-10,000	4,963 contacts →
	Partial evidence “Sophos is a cybersecurity leader defending organizations globally with an AI-driven platform and expert-led services.” Source: RevenueBase Database · checked Sep 1, 2026
2	Sailpoint	Indirect evidence	London, United Kingdom	1,001-5,000	3,059 contacts →
	Indirect evidence “SailPoint equips the modern enterprise to seamlessly manage and secure access to applications and data through the lens of identity – at speed and scale.” Source: RevenueBase Database · checked Sep 1, 2026
3	Darktrace	Partial evidence	Cambridge, United Kingdom	1,001-5,000	2,590 contacts →
	Partial evidence “Darktrace is a global leader in AI cybersecurity, providing the essential cybersecurity platform to secure organizations today and for an ever-changing future.” Source: RevenueBase Database · checked Sep 1, 2026
4	Zerofox	Indirect evidence	United Kingdom	501-1,000	894 contacts →
	Indirect evidence “ZeroFox is the solution to discover, validate, and disrupt external cyber threats before they harm revenue or reputation.” Source: RevenueBase Database · checked Sep 1, 2026
5	SISA	Partial evidence	Leicester, United Kingdom	201-500	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 Sep 1, 2026
6	Claroty	Indirect evidence	London, United Kingdom	501-1,000	729 contacts →
	Indirect evidence “Claroty has redefined cyber-physical systems (CPS) protection with an unrivaled industry-centric platform built to secure mission-critical infrastructure.” Source: RevenueBase Database · checked Sep 1, 2026
7	Everfox	Indirect evidence	London, United Kingdom	1,001-5,000	635 contacts →
	Indirect evidence “Everfox delivers trusted connectivity to protect the world's most critical environments, safeguarding the sensitive information behind decision advantage.” Source: RevenueBase Database · checked Sep 1, 2026
8	Withsecure	Partial evidence	London, United Kingdom	501-1,000	614 contacts →
	Partial evidence “WithSecure™ is Europe's cybersecurity partner of choice.” Source: RevenueBase Database · checked Sep 1, 2026
9	Lodge Security	Indirect evidence	Cirencester, United Kingdom	1,001-5,000	419 contacts →
	Indirect evidence “Unlike traditional security providers, we're redefining what protection means in today's world.” Source: RevenueBase Database · checked Sep 1, 2026
10	Bridewell	Indirect evidence	Edinburgh, United Kingdom	201-500	304 contacts →
	Indirect evidence “Bridewell is the trusted cyber security partner for organisations operating within Critical National Infrastructure (CNI), as well as companies who want the highest standard of…” Source: RevenueBase Database · checked Sep 1, 2026
11	Quorum Cyber	Indirect evidence	Edinburgh, United Kingdom	201-500	292 contacts →
	Indirect evidence “At Quorum Cyber, we're on a mission to help good people win.” Source: RevenueBase Database · checked Sep 1, 2026
12	QODEA	Partial evidence	London, United Kingdom	201-500	237 contacts →
	Partial evidence “Qodea, powered by Beyond, are a technology group building the world's leading cloud and cybersecurity solutions, from foundational infrastructure to advanced AI.” Source: RevenueBase Database · checked Sep 1, 2026
13	The Redesign Group	Partial evidence	London, United Kingdom	201-500	201 contacts →
	Partial evidence “The Redesign Group is a global technology and cybersecurity consulting firm leveraging design thinking, interdependent subject matter expertise, and emerging technology solutions…” Source: RevenueBase Database · checked Sep 1, 2026
14	Intragen	Indirect evidence	London, United Kingdom	201-500	188 contacts →
	Indirect evidence “Intragen is a cyber security business focused on managed Identity solutions and services.” Source: RevenueBase Database · checked Sep 1, 2026
15	Exclusive Networks UK	Partial evidence	Mansfield, United Kingdom	201-500	168 contacts →
	Partial evidence “Exclusive Networks is a global trusted cybersecurity specialist for digital infrastructure helping to drive the transition to a totally trusted digital future for all people and…” Source: RevenueBase Database · checked Sep 1, 2026
16	Cyberfort	Indirect evidence	Thatcham, United Kingdom	51-200	160 contacts →
	Indirect 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 Sep 1, 2026
17	Cybersec Consulting	Indirect evidence	London, United Kingdom	201-500	141 contacts →
	Indirect evidence “CyberSec Consulting, headquartered in the UAE and serving the iMETA market, is a distinguished professional Cyber Security and Consulting services company.” Source: RevenueBase Database · checked Sep 1, 2026
18	Cipher سايڤر	Partial evidence	London, United Kingdom	201-500	135 contacts →
	Partial evidence “At Cipher, we're redefining digital security as the premier cybersecurity leader in the Middle East.” Source: RevenueBase Database · checked Sep 1, 2026
19	Instil	Indirect evidence	Belfast, United Kingdom	51-200	120 contacts →
	Indirect evidence “At Instil, we help technology brands transform, innovate and disrupt their markets with secure, category-defining software.” Source: RevenueBase Database · checked Sep 1, 2026
20	Bulletproof Cyber Security	Indirect evidence	London, United Kingdom	51-200	118 contacts →
	Indirect evidence “Bulletproof is now part of WorkNest Secure.” Source: RevenueBase Database · checked Sep 1, 2026
21	Foresite Cybersecurity	Indirect evidence	Farnborough, United Kingdom	51-200	100 contacts →
	Indirect evidence “As the world becomes more connected, our lives and businesses are more vulnerable.” Source: RevenueBase Database · checked Sep 1, 2026
22	Drawbridge	Partial evidence	London, United Kingdom	51-200	97 contacts →
	Partial evidence “Drawbridge is a premier provider of cybersecurity software and solutions to the alternative investment and wealth management industry.” Source: RevenueBase Database · checked Sep 1, 2026
23	Caretower An Integrity360 Company	Indirect evidence	London, United Kingdom	201-500	97 contacts →
	Indirect evidence “As an independent IT security specialist, Caretower provide comprehensive solutions to individual problems, thus allowing our recommendations to be unbiased.” Source: RevenueBase Database · checked Sep 1, 2026
24	Nomios Uk&i	Indirect evidence	Manchester, United Kingdom	51-200	96 contacts →
	Indirect evidence “We are committed to developing solutions and services that secure and connect the increasingly complex digital landscape.” Source: RevenueBase Database · checked Sep 1, 2026
25	Cyberone	Indirect evidence	London, United Kingdom	51-200	96 contacts →
	Indirect evidence “CyberOne is a Microsoft Security Elite Partner and one of only 100 global Microsoft partners recognised with Microsoft-Verified Managed XDR solution status.” Source: RevenueBase Database · checked Sep 1, 2026

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: cybersecurity startups. 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 cybersecurity startups.
Partial evidence: Its own public description names part of cybersecurity startups, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name cybersecurity startups. 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 1,362 cybersecurity startups based in the United Kingdom

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Cybersecurity startups based in the United Kingdom at a glance

As of Sep 1, 2026

43.6%Verified-email coverage

15.7%Mobile-number coverage

21.0Average contacts per company

1-10Median size (employees)

43.0%Largest-city concentration · London

Sep 1, 2026Page data refreshed

Companies by employee count

1-10

808

11-50

398

51-200

109

201-500

501-1,000

1,001-5,000

5,001-10,000

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 cybersecurity startups, 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 “cybersecurity startups”. 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 cybersecurity startups), 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 cybersecurity startups, 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, 12,476 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 September 1, 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.

Cybersecurity startups 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 cybersecurity startups, 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 cybersecurity startups are there based in the United Kingdom?

RevenueBase identified 1,362 cybersecurity startups headquartered in the United Kingdom as of September 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?

Sophos, headquartered in Abingdon, tops this list with the largest team on record.

Which city has the most cybersecurity startups?

London leads with 586 headquartered companies, followed by Manchester (56) and Cheltenham (23).

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 12,476 verified decision-maker contacts tracked across these 1,362 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 1, 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.