Seed Cybersecurity companies in London

Companies defending or attacking software, networks, and cloud infrastructure. Filtered to Seed-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 Seed Cybersecurity companies in London”

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

1
Intruder· London, England, United Kingdom
Intruder's continuous exposure management platform helps security, IT, and engineering teams stop breaches before they start. By unifying AI penetration testing, attack surface monitoring, cloud security, and vulnerability management in one intuitive platform, Intruder gives stretched teams an always-on security source of truth. Our approach focuses on continuous automated scanning using expertise and agentic solutions to ensure that the findings we deliver are accurate, prioritized by real-world risk, and ready to act on.Founded in 2015 by Chris Wallis, a former ethical hacker turned corporate blue teamer, Intruder is now protecting over 3,000 companies worldwide. Intruder has been awarded multiple accolades, was selected for GCHQ’s Cyber Accelerator, included on Deloitte’s Tech Fast 50 2023 list as the fastest-growing cybersecurity company in the UK and was named in G2’s 2026 Best Software Awards.============================We're hiring! https://careers.intruder.io============================
- Seed
- 81 employees
- Founded 2015
2
SecureFlag· Canary Wharf, All Saints, West India Quay, Westferry, Heron Quays, South Quay, Island Gardens, East India Dock Road, East India, London Arena, Coldharbour, Limehouse, Millwall, Mudchute, Cubitt Town, Blackwall, Poplar, England, United Kingdom
SecureFlag helps organizations prevent vulnerabilities at scale by embedding security into every stage of software development, from architecture decisions to the moment code is written.From secure design to secure code, we transform how enterprises manage application risk.AI coding assistants have rapidly changed the risk equation. Developers are shipping faster than ever—and shipping more vulnerabilities with them, at a pace traditional AppSec tools can't match.As a Developer Security Enablement Platform, SecureFlag brings hands-on secure coding training and automated threat modeling into one place:-ThreatCanvas generates complete threat models in seconds, making risks visible at the design stage—before AI-generated (or human-written) code ever hits the repo.-SecureFlag Training upskills developers in live development environments, teaching them to recognize and fix the exact vulnerabilities AI tools are most likely to introduce.-Compliance reporting delivers continuous, audit-ready evidence across standards such as ISO, SOC 2, PCI, HIPAA, and ASVS.What enterprise teams see:➔ 21% fewer new security tickets➔ 27% faster vulnerability remediation➔ 24% less time spent on security rework➔ 2.4x ROI within 12 monthsTrusted by 300+ organizations in 30+ countries to turn secure-by-design from a principle into a measurable security control.Book a demo to see SecureFlag in action.
- Seed
- 71 employees
- Founded 2019
3
Goldilock Secure· London, England, United Kingdom
In today’s hyper-connected digital world, protecting any organization's assets against novel, sophisticated and aggressive cyber threats means reversing that hyper-connection when needed...powerfully, completely and outside the view of adversaries. Cutting them off while maintaining control of systems is essential.Goldilock FireBreakTM already protects water, energy, transportation and government infrastructure, providing a balance of security and business continuity, as well as being the world's AI Kill Switch. Our FireBreakTM️ Physical Connection Controller is a new breed of device that is controlled remotely, invisibly to the network, and allows you to disconnect either entire networks or selected segments at the physical level. We enforce total physical isolation-based segmentation. Any network, whether large enterprise, service provider, critical infrastructure or defense sector, needs to protect services, data, and business operations. Using FireBreakTM️ physical connection controller “uniquely achieves what no other solution can.” says Gregory Akers, Advanced Security Research, CISCO. Goldilock delivers advanced cyber defense solutions for network and infrastructure protection at the physical layer. FireBreakTM️ is a powerful physical connection controller that remotely, and invisibly, allows the disconnection of either whole networks or selected segments.
- Seed
- 45 employees
- Founded 2020
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 Seed Cybersecurity companies in LondonRun
- Founders of Seed Cybersecurity companies in LondonRun
500 free credits on sign-up, no card needed.
4
SURF SECURITY· London, England, United Kingdom
The business landscape is fundamentally changing – the way and location of work has been transformed. Furthermore, with mass migration to the cloud, SaaS is vital. All this creates new risks - numerous points of access from multiple devices and multiple locations increase the attack surface. To address these attacks, your security solution should fundamentally change as well. That's where SURF enters.SURF provides users with freedom of work, letting them interact with applications, data, and each other securely. It addresses the critical business asset neglected by security experts for years: The browser.The browser is the access frontier for everything: users, data, corporate assets, applications, development activities - and cyber criminals, too.SURF Security has transformed the browser into your strongest security asset while providing complete end-user privacy – all with full compliance. Through this centralized platform, SURF insists on identity-first access to all SaaS and corporate assets to guarantee a secured and frictionless user experience. SURF enhances security, performance, and productivity for end-users and applications – faster than ever before.
- Seed
- 32 employees
- Founded 2021
5
BLOCKAPT· 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
Award-winning BlockAPT is redefining cybersecurity with an AI-powered, autonomous, self-defending platform built to protect modern digital ecosystems at speed and scale.Built on Cybersecurity Mesh Architecture, BlockAPT unifies security, risk, compliance, cloud, infrastructure, and operational tools into one intelligent command layer. Vendor-agnostic, modular and highly scaleable by design, the platform unifies security, risk, compliance, cloud, infrastructure, and operational tools into a single intelligent ecosystem. It eliminates silos, reduces complexity, and enables organisations to detect, respond to, orchestrate, and neutralise threats in real time.Our AI-powered automation reduces manual workloads, accelerates response times, simplifies compliance, and delivers real-time visibility across on-premise, cloud, multi-cloud, and hybrid environments. With one-hour deployment and a flexible Pay-as-you-Grow model, BlockAPT helps organisations of all sizes to strengthen cyber resilience without disruption, optimise existing technology investments, and achieve measurable ROI from day one.The platform is built around three core modules:UNIFY - integrates tools, systems, data, and workflows into one intelligent real-time view.CONTROL - orchestrates and automates security operations in real time through AI-powered playbooks.QUANTUM - provides quantum-secure communication and asset protection for data in motion and data at rest.BlockAPT also delivers unique automated cloud migration across cloud and multi-cloud environments in just a few clicks, accelerating secure digital transformation.BlockAPT sits at the intersection of AI, autonomous cyber defence, platform consolidation, cloud transformation, and quantum-secure resilience - creating a compelling opportunity for customers, partners, investors, and potential acquirers.For more information:www.blockapt.com | raj.meghani@blockapt.com
- Seed
- 21 employees
- Founded 2019

6
Falconfeeds.io· London, England, United Kingdom
Falcon Feeds.io: Your 24/7 Cyber Threat Intelligence Partner.Falcon Feeds.io is a cutting-edge, cloud-native SaaS platform that specializes in cyber threat intelligence. It vigilantly monitors and delivers the latest security incidents and insights on threat actors from around the globe, around the clock. Our expansive coverage includes the surface web, Tor networks, and Telegram channels.With Falcon Feeds.io, you can:Continuous Monitoring: Keep a watchful eye on threat actors, ransomware attacks, DDoS attacks, and other security incidents around the clock.Comprehensive Analysis: Stay informed about the most affected geographies, industries, organizations, and domains in real-time.Unrestricted Access: Gain unlimited access to our extensive threat feed database to empower your security measures.Customizable Alerts: Configure alerts tailored to new threats related to specific threat actors, incident categories, countries, industries, organizations, and domains.Seamless Integration: Utilize our robust API and Webhook integration for a smooth and streamlined security workflow.Real-Time Notifications: Get instant notifications through Slack, Microsoft Teams, and email, ensuring you never miss a critical update.Falcon Feeds.io is not just a platform; it's a partner in your cyber defense strategy, designed to give you a decisive advantage against evolving digital threats.
- Seed
- 19 employees
- Founded 2023
7
MIRACL | The login you love· London, England, United Kingdom
MIRACL provides the world’s only user-friendly, single step Multi-Factor Authentication (MFA) and Digital Signing service. Secure MFA in 2 seconds.MIRACL Trust® ID blocks 98% of all attacks* and eliminates the need for outdated security practices such as passwords, SMS Texts, push notifications and key-cards. The use of true two-factor authentication coupled with the latest Zero Knowledge Proof (ZKP) technology means no personal data is stored or transmitted and there are no "honey-pots" of data exposed to attack keeping MIRACL Trust out of scope for GDPR.MIRACL Trust® Proof allows every user to cryptographically sign any digital asset such as a transaction payment, KYC document transfer, user uploaded content, user action or binding agreement.Usability is paramount, no additional user enrolment steps are required and users authenticate & sign using a simple PIN. Without the requirement for hardware, mobiles or fiddly second steps, your users will love the simplicity and you will appreciate the reduction in support and maintenance overheads.MIRACL Trust® integrates easily into any web or mobile application through a cloud-based service, and has no dependence on client hardware of any kind. Provisioned as a PAYG service at a fraction of the cost of competing hardware solutions or SMS texts, MIRACL Trust® ID can be integrated with any OIDC compliant platform such as ForgeRock, WSO2, Okta and Auth0 just to name a few.Capable of scaling to millions of users overnight, a combination of usability, security and cost make it possible to deploy strong MFA to large B2C networks where it was previously impossible or impractical.Learn more at: www.miracl.com* Calculated from the 2019 Verizon Data Breach Investigations Report, based on Man-in-the-Middle, Phishing and Credential Stuffing (bot) attack frequencies recorded in 2018.
- Seed
- 17 employees
- Founded 2011
8
Ploy· London, England, United Kingdom
Ploy is the most intuitive way to manage all access to your cloud environments, empowering organizations to gain complete visibility and turn any type of access into temporary access. From initial onboarding to full lifecycle management, Ploy makes access governance simple and effective. With thoughtfully designed workflows and robust automation, teams can streamline their approach to managing user access, reducing risk, and ensuring compliance across the board.Trusted by forward-thinking, tech-driven companies, Ploy transforms how businesses handle access to critical systems, facilitating smoother audits and enhancing security without the administrative burden. Ploy helps teams stay secure, compliant, and focused on scaling their core operations efficiently.
- Seed
- 12 employees
- Founded 2023
9
ResilientX Security· London, England, United Kingdom
ResilientX Security is a fast-growing Cyber Security company that helps organizations of all sizes identify, quantify and manage their cyber risks and cyber exposure. At ResilientX, we are committed to delivering state-of-the-art security solutions to help organizations safeguard their digital assets and maintain compliance. Our First-Party and Third-Party Risk and Exposure Management platform is designed for those who take security and compliance seriously.Our Solutions:Unified Exposure Management (UEM): ResilientX UEM provides a holistic approach to proactive security. Our platform is engineered to automatically identify assets, perform in-depth security testing, and reduce risks across your entire attack surface. We cover a broad spectrum of potential vulnerabilities, including IPs and domains, web applications, cloud environments, network devices and services, APIs, and dark web threats.Third-Party Risk Management (TPRM):Our TPRM solution offers a comprehensive 360-degree approach to managing risks posed by suppliers, vendors, and strategic business partners. ResilientX TPRM enables you to assess, monitor, and mitigate these risks effectively, automating and streamlining your assessment and monitoring activities. Our solution can save up to 6 hours of cyber due-diligence per vendor each month.Interested to see ResilientX in action? https://resilientx.com/demo
- Seed
- 11 employees
- Founded 2022
10
HYPERBUNKER· London, England, United Kingdom
When IT, identity, and network trust are gone, HyperBunker is what remains.A physical recovery vault for the moment everything digital fails.Bare metal recovery of OT and critical systems.No Active Directory. No cloud. No trusted network assumptions.Used by incident response teams and OT engineers who restart systems after total compromise.Critical infrastructure operators treat it as the first known-good state.This is not backup.This is the starting point when the model breaks.
- Seed
- 10 employees
- Founded 2024

Reveal 8 more·500 free credits, no card

Find engineers at Seed Cybersecurity companies in London

Searching for “engineers at top Seed Cybersecurity companies in London” surfaces this slice of the market. The list above ranks Cybersecurity companies headquartered in London whose latest disclosed round is Seed, by current headcount, drawn from public LinkedIn and Crunchbase records. With 13 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 - Seed, 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 Seed Cybersecurity companies in London hiring” or “founders of Seed 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 Seed 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: Fri, 23 Oct 2026 05:00:48 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: Fri, 23 Oct 2026 05:00:48 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.