Series A Cybersecurity companies in London

Companies defending or attacking software, networks, and cloud infrastructure. Filtered to Series A-stage companies headquartered in London.

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Ranked by current headcount across Series A Cybersecurity companies in London. Refreshed daily.

1
SenseOn· London, England, United Kingdom
SenseOn deploys alongside all of your existing tools, unifying them into a single investigation plane and augmenting your team with cross-domain correlation, analytics, and AI-accelerated resolution under human governance. Every AI containment action requires human approval before execution.
- Series A
- 57 employees
- Founded 2017
2
Ubisecure· London, England, United Kingdom
Ubisecure is a Europe-based Identity Services specialist and offers a comprehensive CIAM (Customer Identity & Access Management) & LEI (Legal Entity Identifier) platform to manage the digital identities of customers, citizens, workforce and organisations. Through our RapidLEI service, the company is the largest accredited LEI issuer globally and has issued verified organisation identities to over 200k organisations. Ubisecure works with enterprises, banks, fintech/regtech, and Government for internal and client use of digital identity in digital identity management, KYC/KYB, and legal entity regulatory requirements, and delivering on its unique “true B2B Identity Management” proposition. True B2B identity management is only made possible by combining strongly authenticated individuals with highly assured organisation identities to allow them to express who they are, who they represent and the rights they have when doing so. The hybrid approach to Identity Management allows Ubisecure to uniquely achieve this proposition. Ubisecure’s global mission is to help enterprises embrace the global digital identity ecosystem, improve operational effectiveness and build trusted business relationships.
- Series A
- 53 employees
- Founded 2002
3
Maze· London, England, United Kingdom
Maze uses AI agents to investigate vulnerabilities across code and cloud using a unified engine. Maze agents understand your environment and prove which findings across code and cloud are exploitable. Once a vulnerability is confirmed exploitable, agents generate a fix and route it to the developer or AI agent who owns that code.Learn more at mazehq.com.
- Series A
- 47 employees
- Founded 2024
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4
Venari Security· London, England, United Kingdom
Venari Security provides organisations with advanced visibility into their encrypted attack surface, ensuring regulatory compliance and privacy adherence through our cryptographic discovery tool.Our focus is on crypto agility which helps you assess both external and internal cryptographic risks, preparing your business now and for the quantum future.
- Series A
- 45 employees
- Founded 2021
5
ThreatAware· London, England, United Kingdom
Know what’s protected and gain a trusted view of your endpoints. ThreatAware delivers verified visibility into endpoint security posture, enabling security and IT teams to answer the question, “Are we protected?” Within an hour, teams gain a single source of truth across their endpoint estate. The platform continuously identifies devices, validates that security controls are working as intended, and unifies disconnected tools into one clear view, so teams can see what’s protected, where gaps exist, and where to focus remediation.
- Series A
- 43 employees
- Founded 2019

6
Equixly· London, England, United Kingdom
Penetration testing, reimagined with AI.Equixly is a proactive offensive security platform built for modern applications and APIs. As applications become increasingly API-driven, traditional penetration testing can’t keep pace. Tests are scheduled periodically, take weeks to complete, and reflect a moment in time while applications, APIs, and business logic change constantly.Equixly changes that model. Powered by an Agentic AI Hacker, Equixly continuously discovers APIs, understands business logic, and actively attacks applications to uncover real, exploitable threats before attackers do.In a world where attackers already use AI to move faster, operate with tenacity, and scale their attacks, Equixly acts as an equalizer, giving organizations an autonomous adversary of their own and enabling a shift from reactive testing to pre-emptive offensive security.
- Series A
- 38 employees
- Founded 2022
7
CultureAI· London, England, United Kingdom
CultureAI is the AI Usage Control Platform that helps organisations enable safe, compliant AI adoption. With up to 78% of employees already using tools like ChatGPT and Copilot—often without approval—CultureAI gives security teams real-time visibility into sanctioned and shadow AI use, detects risky behaviour at the prompt level, and nudges users before mistakes happen. Deployed in minutes, it closes blind spots, reduces risk, and keeps innovation moving safely at scale.
- Series A
- 35 employees
- Founded 2015
8
Cydome· London, England, United Kingdom
Cydome is a pioneer of maritime-specific cyber protection and risk management. Its class-endorsed, ISO-certified, and award-winning solutions secure and simplify maritime cyber protection, while 24x7 SOC managed services take away the cyber ops overhead. Cydome's solutions provide holistic protection for IT, OT, and communications assets in real-time; proactive, automated vulnerability scanning and risk management; full asset management and risk visibility via a centralized fleet-wide dashboard; and compliance automation – all without the hassle of complex implementations and with “zero-touch” operation on board. Cydome's unique, proprietary technology uses AI algorithms specifically trained for maritime use-cases, and follows standard cybersecurity frameworks such as NIST to proactively identify, protect, detect, and respond to known and unknown cyber threats.Cydome caters to all types of maritime vessels and on-shore facilities, including container ships, bulkers, gas & oil tankers, superyachts, cruise lines, offshore vessels, rigs and offshore facilities, ports, as well as dedicated vessels such as car carriers and autonomous research vessels.Follow us to get the latest news on maritime cybersecurity.Headquartered in the U.K., Cydome has local support also in Germany, Greece, Japan, Singapore, U.S.A. and the middle east.
- Series A
- 35 employees
- Founded 2019
9
RevEng.AI· London, England, United Kingdom
At RevEng.AI, we specialise in developing foundational deep learning AI models that possess a profound understanding of binary machine code, both semantically and syntactically. Our AI is designed to rigorously validate the integrity of software supply chains at a binary level, ensuring uncompromising security and trustworthiness in digital ecosystems.
- Series A
- 27 employees
- Founded 2022
10
Cybertonica Ltd· London, England, United Kingdom
Cybertonica uses Machine Learning and Artificial Intelligence to manage risk and fraud, increasing trust and growing frictionless banking and m/e-payments globally. Cybertonica’s service increases conversion and sales by up to 25% while managing card-not-present and other categories of fraud at world-class compliant standards. Our goal is to build Trust in Transaction.Cybertonica has won numerous distinctions and awards since its product came to market, including the “Best Use of Payments Data Award” at Emerging Payments Awards 2018 and the “Best Data Analytics and Science Award” at Merchant Payments Ecosystem Awards 2018. Cybertonica also was named finalist for the “FinTech Start-up of the Year Award” at EWPN Awards 2019 and received the “Best New Back Office Innovation Award” at the Emerging Payments Awards 2017.Our new ScreenWiZeTM product adds device risk management through SDKs (iOS and Android) to the mobile authentication and malware prevention capabilities of our customers whether banks, acquirers, merchants or transactions security. We are PSD2 ready and GDPR compliant. Cybertonica’s vision is for a world of frictionless transaction and trust in 99.9% of transactions. Visit cybertonica.com to join us and build the future of Trust in Transaction.
- Series A
- 12 employees
- Founded 2015

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Find engineers at Series A Cybersecurity companies in London

Searching for “engineers at top Series A Cybersecurity companies in London” surfaces this slice of the market. The list above ranks Cybersecurity companies headquartered in London whose latest disclosed round is Series A, by current headcount, drawn from public LinkedIn and Crunchbase records. With 10 matching companies in Refolk’s index, this is a tight read on where the Cybersecurity talent in London is heating up.

Three filters at once narrows the field hard. The companies that survive all three - Series A, Cybersecurity, in London - are usually the most targeted recruiting pool a hiring manager can ask for. Senior engineers, founding designers, and product leads here are about to become Cybersecurity’s next operators and angel investors.

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Refolk pulled Cybersecurity companies headquartered in London whose latest disclosed funding round is Series A from public LinkedIn and Crunchbase records, ranked them by current employee count, and kept those with at least 3 employees. The list refreshes once a day.

Last refreshed: Wed, 05 Aug 2026 21:29:10 GMT

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