Company lists · Data refreshed September 2026

Top 25 Online data security companies based in the United Kingdom

Name: Online data security companies based in the United Kingdom
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 21, 2026 920 companies tracked

RevenueBase identified 920 online data security companies headquartered in the United Kingdom as of September 2026 and tracks 16,098 professional contacts across them, including 6,454 with verified work emails. London is the largest hub.

This list covers online data 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 September 21, 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 HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 21, 2026 86% judged on-target in blind review

920Companies

16,098Contacts tracked

6,454Verified emails

Explore this list → Free signup · no credit card · 500 free credits

The 25 largest online data security companies based in the United Kingdom

Ranked by team size

Top 25 of 920 online data security companies based in the United Kingdom, ranked by team size, largest first. Data refreshed Sep 21, 2026. RevenueBase Smart Search rates how each company's information relates to online data security companies: 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	Indirect evidence	Abingdon, United KingdomHQ checked Sep 21, 2026	5,001-10,000	4,925 contacts →
	Indirect evidence “Sophos is a cybersecurity leader defending organizations globally with an AI-driven platform and expert-led services.” Source: RevenueBase Database · checked Sep 21, 2026
2	MTI	Strong evidence	Staines-upon-thames, United KingdomHQ checked Sep 21, 2026	201-500	764 contacts →
	Strong evidence “MTI provides award-winning, end-to-end technology solutions and services in cyber security and data centre for over 35 years.” Source: RevenueBase Database · checked Sep 21, 2026
3	Securityhq	Partial evidence	London, United KingdomHQ checked Sep 21, 2026	501-1,000	502 contacts →
	Partial evidence “SecurityHQ, a global cybersecurity company pioneering Security Performance Engineering for stronger operational performance and resilience.” Source: RevenueBase Database · checked Sep 21, 2026
4	Bridewell	Partial evidence	Reading, United KingdomHQ checked Sep 21, 2026	201-500	303 contacts →
	Partial 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 21, 2026
5	Quorum Cyber	Indirect evidence	Edinburgh, United KingdomHQ checked Sep 21, 2026	201-500	297 contacts →
	Indirect evidence “At Quorum Cyber, we're on a mission to help good people win.” Source: RevenueBase Database · checked Sep 21, 2026
6	Obrela	Partial evidence	London, United KingdomHQ checked Sep 21, 2026	201-500	242 contacts →
	Partial evidence “Obrela Security Industries is a global provider of cyber security services.” Source: RevenueBase Database · checked Sep 21, 2026
7	Deepcytes Cyber Labs UK	Partial evidence	London, United KingdomHQ checked Sep 21, 2026	51-200	177 contacts →
	Partial evidence “Whether you’re a business or an individual, digital threats to your precious data and assets can come in any form - external or internal.” Source: RevenueBase Database · checked Sep 21, 2026
8	Sapphire	Indirect evidence	Newcastle Upon Tyne, United KingdomHQ checked Sep 21, 2026	51-200	168 contacts →
	Indirect evidence “Sapphire delivers comprehensive cyber solutions tailored to your needs, spanning across consultancy, managed services, IT/OT and beyond.” Source: RevenueBase Database · checked Sep 21, 2026
9	Exclusive Networks UK	Indirect evidence	Alton, United KingdomHQ checked Sep 21, 2026	201-500	165 contacts →
	Indirect 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 21, 2026
10	Cyberfort	Strong evidence	Thatcham, United KingdomHQ checked Sep 21, 2026	51-200	159 contacts →
	Strong 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 21, 2026
11	Performanta	Partial evidence	Maidenhead, United KingdomHQ checked Sep 21, 2026	51-200	156 contacts →
	Partial evidence “Performanta is a global cybersecurity and data risk management company dedicated to protecting people where data matters most.” Source: RevenueBase Database · checked Sep 21, 2026
12	Khipu Networks	Partial evidence	Fleet, United KingdomHQ checked Sep 21, 2026	51-200	125 contacts →
	Partial evidence “KHIPU Networks is an award winning international Cyber Security Company delivering a wide range of network, wireless and security solutions, technologies and services across…” Source: RevenueBase Database · checked Sep 21, 2026
13	Bulletproof Cyber Security	Indirect evidence	London, United KingdomHQ checked Sep 21, 2026	51-200	123 contacts →
	Indirect evidence “Bulletproof is now part of WorkNest Secure.” Source: RevenueBase Database · checked Sep 21, 2026
14	Conosco	Indirect evidence	London, United KingdomHQ checked Sep 21, 2026	51-200	105 contacts →
	Indirect evidence “Cybersecurity specialists providing technology and telecoms solutions that gives you the leadership, experience and resilience you need to build and secure the future of work.” Source: RevenueBase Database · checked Sep 21, 2026
15	ITC Secure	Partial evidence	London, United KingdomHQ checked Sep 21, 2026	51-200	87 contacts →
	Partial evidence “ITC Secure is an advisory-led cyber security services company.” Source: RevenueBase Database · checked Sep 21, 2026
16	Wavenet Cyberguard	Partial evidence	Stourport-on-severn, United KingdomHQ checked Sep 21, 2026	201-500	86 contacts →
	Partial evidence “CyberGuard Technologies is the security division of Wavenet.” Source: RevenueBase Database · checked Sep 21, 2026
17	Amethyst Risk Management	Indirect evidence	Basingstoke, United KingdomHQ checked Sep 21, 2026	11-50	85 contacts →
	Indirect evidence “Amethyst Risk Management is a leading cybersecurity consultancy supplying expert services and support to the UK Government, Defence, Operators of Essential Services, and the…” Source: RevenueBase Database · checked Sep 21, 2026
18	Cybersmart	Indirect evidence	London, United KingdomHQ checked Sep 21, 2026	51-200	84 contacts →
	Indirect evidence “Cybersecurity should be simple.” Source: RevenueBase Database · checked Sep 21, 2026
19	Foregenix	Partial evidence	Swindon, United KingdomHQ checked Sep 21, 2026	51-200	80 contacts →
	Partial evidence “When your business relies on security, compliance and a strong reputation for taking care of your customers, you need a partner that understands your ethos, your challenges and…” Source: RevenueBase Database · checked Sep 21, 2026
20	Reliance Cyber	Indirect evidence	Waterloo, United KingdomHQ checked Sep 21, 2026	51-200	80 contacts →
	Indirect evidence “At Reliance Cyber, we believe in truly partnering with our customers.” Source: RevenueBase Database · checked Sep 21, 2026
21	Virtual IT LTD	Indirect evidence	South & West Hampstead, United KingdomHQ checked Sep 21, 2026	51-200	79 contacts →
	Indirect evidence “Virtual IT are a leading provider of cyber-secure cloud and managed IT services in the UK, entrusted by over 700 businesses and schools as their end-to-end technology partner.” Source: RevenueBase Database · checked Sep 21, 2026
22	White HAT An Epam Company	Partial evidence	London, United KingdomHQ checked Sep 21, 2026	51-200	77 contacts →
	Partial evidence “White Hat, part of the EPAM group, is an award-winning cyber intelligence and offensive security company that leverages an attacker’s perspective to shape innovative, proactive…” Source: RevenueBase Database · checked Sep 21, 2026
23	Saepio Information Security	Partial evidence	High Wycombe, United KingdomHQ checked Sep 21, 2026	51-200	74 contacts →
	Partial evidence “Saepio increase awareness, reduce risk and improve security in a continually evolving threat landscape.” Source: RevenueBase Database · checked Sep 21, 2026
24	Dionach By Nomios	Partial evidence	Oxford, United KingdomHQ checked Sep 21, 2026	51-200	73 contacts →
	Partial evidence “Dionach by Nomios has over 25 years of expertise in information security, supporting organisations in building resilience against ever‑evolving cyber threats.” Source: RevenueBase Database · checked Sep 21, 2026
25	CSA Cyber	Indirect evidence	Gloucester, United KingdomHQ checked Sep 21, 2026	51-200	69 contacts →
	Indirect evidence “Modern cyber resilience demands more than isolated controls.” Source: RevenueBase Database · checked Sep 21, 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: online data 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 online data security companies.
Partial evidence: Its own public description names part of online data security companies, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name online data 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 920 online data security companies based in the United Kingdom

See the full list, filter by size, metro and specialty, and get verified emails and direct dials for all 6,454 reachable decision-makers.

Free signup · no credit card

View the full list →

Online data security companies based in the United Kingdom at a glance

As of Sep 21, 2026

40.1%Verified-email coverage

17.5Average contacts per company

1-10Median size (employees)

37.1%Largest-city concentration · London

Sep 21, 2026Page data refreshed

Companies by employee count

1-10

570

11-50

247

51-200

201-500

501-1,000

1,001-5,000

5,001-10,000

10001+

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 920 companies.

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 online data 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 “online data 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 online data 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 online data 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, 6,454 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 21, 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.

Online data security companies by metro

Online data security companies in London341
Online data security companies in Manchester39

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 online data 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 online data security companies are there based in the United Kingdom?

RevenueBase identified 920 online data security companies 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 online data security companies?

London leads with 341 headquartered companies, followed by Manchester (39) and Birmingham (19).

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 6,454 verified decision-maker contacts tracked across these 920 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 21, 2026.

Ready to reach these companies? Verified emails and direct dials for all 920 online data security companies based in the United Kingdom. Start with a free account, no credit card.

Download this list →

Related lists

Online data security companies by geography

Browse the directory

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.