Series A Cybersecurity companies in London

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

Hiring from these companies? Find the people who work there.

Change the role to whoever you are hiring, or narrow the list below. 500 free credits on sign-up, no card needed.

Built from a search like: “Top Series A Cybersecurity companies in London”

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

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
- 58 employees
- Founded 2017
2
ThreatAware· Newington, Waterloo, London Bridge, Southwark, Lambeth North, New Kent Road, Westminster Bridge, Southwark Cathedral, Lambeth, Old Kent Road, South Bank, Borough, Bermondsey, 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
- 48 employees
- Founded 2019
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
- 48 employees
- Founded 2024
Live search
This list is a starting point
I can run a natural-language search across LinkedIn, GitHub, and the open web. Fire one of these, or edit the box up top to match exactly who you're after.
- Engineers at top Series A Cybersecurity companies in LondonRun
- Founders of Series A Cybersecurity companies in LondonRun
500 free credits on sign-up, no card needed.
4
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
- 34 employees
- Founded 2019
5
CultureAI· London, England, United Kingdom
CultureAI gives security teams visibility of every AI tool their people use, and the controls to secure every interaction — without becoming the department of "No."We discover shadow AI across the organisation, classify prompts and uploads in real time, coach people at the moment of risk, and generate audit-ready evidence for the EU AI Act, NIST AI RMF, ISO 42001 and SOC 2. Endpoint-native and cloud-powered, so there is no proxy chokepoint to deploy or maintain.Built in the UK, trusted globally.
- Series A
- 31 employees
- Founded 2015

6
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
- 28 employees
- Founded 2022
7
DynaRisk· London, England, United Kingdom
Identify & Manage Cyber Risks At Scale, with DynaRisk.Our mission at DynaRisk is to provide families and small and large businesses worldwide with the tools they need to face the increasing number of cyber threats. We offer a variety of easy-to-use cyber software solutions, along with cyber risk intelligence and helpline services, backed by our market-leading threat intelligence capabilities for personal and business cyber risk management.Our insurance, loyalty and benefits, and managed service provider clients from across the globe, partner with us to integrate our solutions into their offerings for their customers. Our partners use our software and services to improve loss ratios, increase engagement, drive new business and reach more customers.Find out more: https://dynarisk.com/about-us
- Series A
- 20 employees
- Founded 2015
8
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

Reveal 3 more·500 free credits, no card

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 8 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.

Refolk converts this list into a live search. Ask for “senior engineers at Series A Cybersecurity companies in London hiring” or “founders of Series A Cybersecurity companies in London who left in the last year” and Refolk returns a ranked shortlist with the evidence behind each match.

How this list is built

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 monthly.

Last refreshed: Thu, 29 Oct 2026 00:13:24 GMT

Search this list

Need an even more specific search?

Refolk runs natural-language searches across LinkedIn, GitHub, and the open web. Try one of these:

500 free credits on sign-up, no card needed.

Related lists

See all company lists.

Slice this list a different way

Common questions

How is this ranking built?

The list draws on the public company graph - headcount and growth signals, funding history, and recency. The criteria chips at the top show exactly which filters produced it, and the methodology section explains the ranking.

How fresh is the data?

The underlying index updates continuously and this ranking is rebuilt monthly. Last refreshed: Thu, 29 Oct 2026 00:13:24 GMT. For a list built against the index as it stands today, sign up and run the search live.

Can I find the people inside these companies?

Yes. Ask in plain English - for example "engineering leaders at these companies who joined in the last year" - and I return the specific people, with context on each.

Try it on the search you came here for

Stop building boolean strings. Just describe the person.

Type one sentence. I plan the search, read GitHub, public LinkedIn and Crunchbase records, and the open web as it is right now, and hand back a ranked list with the reason next to every name.

01Describe them
One plain sentence. Role, city, stack, stage, whatever matters to you.
02I read the web live
GitHub, public LinkedIn and Crunchbase records, the open web. Not a database that went stale last quarter.
03You read the shortlist
Ranked, with the reasoning under every name. Open a profile, ask a follow-up, narrow it down.

No boolean, no filters, no seat to buy. One box.
Read at search time, so a profile updated yesterday counts today.
Every step visible as it runs, every name with its reason.

500 free credits on sign-up. No card, no demo call. See real searches.