Reliance Cyber
Reliance Cyber is a UK-based IT services and cybersecurity consulting company with 48 employees and $5M-$25M annual revenue; specializes in penetration testing, threat intelligence, incident response, and managed security services, with a focus on safeguarding organizations in the digital landscape.
Closed Door Security
UK-based cybersecurity firm specializing in penetration testing and security assessments; registered in the UK (SC585645), headquartered in Stornoway, UK; offers professional pentest services as highlighted on their website and supported by external sources.
CodeShield (Cyber Security)
UK-based cybersecurity firm specializing in penetration testing for web apps, networks, and cloud environments; 1 employee; focuses on threat detection and compliance (ISO, PCI, SOC2, Dstp).
Attack Vector Ltd
UK-based cybersecurity firm specializing in penetration testing; offers infrastructure, web app, cloud, social engineering, and mobile testing; registered in London with Company No. 14996130.
Sophos
Cybersecurity software development company based in the United Kingdom; 3,664 employees, $1B revenue, founded 1985, GBP2.8B market cap, $125M funding; offers endpoint, network, cloud security, and penetration testing services; serves 600,000 organizations globally with an AI-driven platform and expert-led services.
UK Pen Testing – A LevelUp Networks service
Cybersecurity company specializing in penetration testing and security assessments; based in London, UK, with services including Penetration Testing as a Service, Web Application Penetration Testing, Red Team, Cloud Security, Phishing, Firewall Audits, and Ransomware Assessments; explicitly confirmed UK address in London.
Laneden Ltd
Cybersecurity company specializing in penetration testing, threat simulation, and compliance testing; based in United Kingdom with 1 employee, founded in 2019. Offers services including penetration testing, social engineering, web app security, and infrastructure reviews, focusing on identifying security vulnerabilities and quantifying risks.
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NeedSec Limited
UK-based cybersecurity company specializing in penetration testing; headquartered in London, with a registered office at 86-90 Paul Street, London, England. Provides security testing services to identify system vulnerabilities.
Pentest Limited
UK-based cybersecurity company founded in 2019; registered at 22 Great James Street, London, with company number 11925182; provides manual penetration testing, red teaming, and security consultancy services.
SecurityHQ
UK-based MSSP specializing in penetration testing, MDR, and bespoke cybersecurity services; recognized as a leader by KuppingerCole and Frost & Sullivan; offers 24/7 MXDR, security posture management, and vulnerability detection; CREST accredited.
SensePost
UK-registered ethical hacking team within Orange Cyberdefense; specializes in penetration testing and offensive security services; based in Maidstone, Kent, with official UK Companies House registration.
Techforce
UK-based cybersecurity firm headquartered in Aberdeen and Edinburgh; offers penetration testing, cyber maturity assessments, Cyber Essentials certification, virtual CISO, vulnerability management, and managed security services; specializes in protecting businesses from cyber threats with expert consulting and testing solutions.
Intertek
Intertek is a UK-based provider of quality assurance and testing services, headquartered in London at 33 Cavendish Square. The company explicitly offers penetration testing and cybersecurity assessment services, including vulnerability testing and manual penetration tests, across multiple industries.
4N6
IT services and consulting company specializing in cybersecurity, troubleshooting, diagnostics, post-incident reviews, and digital forensics; offers full penetration testing services including active exploitation, vulnerability analysis, and remediation; based in London, UK with 1 employee, 1,122 monthly website visits, and ranked #11,322,919 globally.
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BSI Cyber Consulting
Cybersecurity company specializing in penetration testing, red team assessments, and information security services; supports CREST-certified pentest offerings and detailed testing procedures; 2 employees, $9.44M revenue, headquartered in Cambridge, UK.
Socura
Cybersecurity company specializing in managed detection and response, digital forensics, incident response, and rapid response services; CREST-approved with formal penetration testing credentials, collaborating with partners like Rootshell Security for pentest services; based in Cardiff, UK, with 30 employees and 32.3% YoY growth.
Bema Cyber Tech Ltd
UK-based IT service provider specializing in cybersecurity; offers penetration testing services; registered in London with a UK office at 124 City Road; provides solutions for public and private sectors to achieve Cyber Essentials certifications.
Sodium Cyber Ltd
Cybersecurity consultancy specializing in penetration testing and security assessments; based in Worcestershire, UK with 2 employees, founded in 2020. Offers web application and infrastructure pentests, cloud security, secure code reviews, and maritime systems security; 208 monthly website visits.
PlutoSec
UK-based cybersecurity provider specializing in penetration testing; emphasizes leadership in UK cybersecurity market with multiple UK addresses and branding; offers comprehensive cybersecurity solutions across major UK cities.
ROSCA Technologies
UK-based cybersecurity consultancy specializing in CREST penetration testing for networks, applications, and cloud; located in London, with a focus on strategic cybersecurity management and testing services.
Mongoose Cyber Security
UK-based cybersecurity company founded in December 2022; provides comprehensive penetration testing services including external, web app, social engineering, internal, wireless, and physical testing; CREST-accredited for formal pentest capabilities; registered in Wilmslow, England (Unit 3, Building 2, The Colony Wilmslow, SK9 4LY).
Syn-Star IT Support
UK-based IT services and consulting company founded in 2002; 13 employees, $2.4M revenue; specializes in business IT support, cybersecurity, and penetration testing with dedicated pentest services; serves SMEs with a focus on reliable, end-to-end IT solutions and security.
Simple IT Distribution Ltd
UK-based software development firm founded in 2015 with 2 employees; provides penetration testing and vulnerability management services using tools like Metasploit, demonstrating active security testing capabilities; has 1,096 monthly website visits and a global rank of #11,686,164.
SIBR
Cybersecurity consultancy and penetration testing firm based in London, UK; 3 employees, founded 2021; offers services including penetration testing, vulnerability management, and cloud security to SMEs; over 20 years of combined security experience.
Bluefort Security
UK-based cybersecurity provider specializing in penetration testing; offers automated pentest solutions like Pentera and holds CREST certification credentials, demonstrating active and certified pentest capabilities • 50-100 employees; Cybersecurity; Founded 2010; Farnborough, UK
HAKFLOW
UK-based cybersecurity firm specializing in blockchain security and penetration testing; provides advanced auditing and active penetration testing services to assess and improve blockchain security measures, with headquarters in London, UK.
Woodsec
UK-based cybersecurity firm specializing in penetration testing and cyber security assurance; founded 2022, with formal registration at Kidderminster, England. The company emphasizes its expertise in advanced IT support, application security, and research, serving clients with boutique, expert cybersecurity services.
KT Secure UK
KT Secure UK is a cybersecurity company based in the United Kingdom, specializing in software code signing, hardware security modules, and penetration testing services; with 2 employees, 150% YoY growth, founded in 2009, and a focus on security assessments, vulnerability testing, and key management.
Boxxe
UK-based IT solutions provider specializing in hardware, software, managed IT services, and cybersecurity; explicitly offers penetration testing (pentest) services as part of its cybersecurity portfolio; registered in England and Wales with a York headquarters.
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Bae Systems
UK-based defense, security, and aerospace company headquartered in London; offers penetration testing, red teaming, and security testing services for organizations, with active cybersecurity operations and service offerings.
Securious - Data and Cyber Security
Cybersecurity compliance and pentesting company based in Exeter, UK; 11 employees with 18.2% YoY growth; founded in 2007; provides PCI DSS, ISO 27001, Cyber Essentials, and penetration testing services to UK and international clients.
Xpertex Ltd
UK-based IT services and consulting firm specializing in cybersecurity, including penetration testing and breach & attack simulation; 9 employees with -6.7% YoY growth; founded 2006; headquartered in Welwyn Garden City, England; active in security assessments, vulnerability analysis, and machine parts manufacturing.
Zepko
Cybersecurity firm based in Guildford, United Kingdom, specializing in penetration testing; offers detailed security assessments using standardized testing methodologies and emphasizes human intervention to enhance resilience.
Cybergen® Security
Cybergen® Security is a UK-based IT services and cybersecurity consulting firm founded in 2023, with a focus on penetration testing, red teaming, and threat mitigation. The company provides CREST-accredited penetration testing and 24/7 managed detection and response, emphasizing proactive security testing and vulnerability identification, despite having only 1 employee.
Protection Group International
Protection Group International is a UK-based security and investigations firm specializing in digital resilience, security consulting, and cyber security services; with 77 employees (+10.6% YoY growth), $15M annual revenue, founded in 2013 in London. PGI provides CREST-aligned penetration testing services, demonstrating formal technical standards, and serves a global client base including governments and NGOs. The company operates in multiple languages and maintains active social media engagement.
Arcanum Information Security
Cybersecurity company specializing in penetration testing and security training; 2 employees with 100% YoY growth; based in Llanegwad Ed, UK; offers external and web application pentest services, training, and media; 15,303 monthly visits, global rank #1,648,340.
Six Degrees
IT Services and Consulting company based in London, UK, with 196 employees and $157.8M annual revenue; specializes in infrastructure, hybrid cloud, Azure management, and FinOps; explicitly offers penetration testing services including Penetration Testing as a Service and Red Teaming with CHECK/CREST accreditation; founded in 2011, with $145.9M in funding and active market presence.
GoDefend (Cyber Security)
Cybersecurity company based in the United Kingdom; specializes in data security software, penetration testing, breach detection, and compliance solutions; 5 employees, founded 2018, $3.3M funding, recent £250K investment to grow threat detection tech; competes with qingteng cloud security and sonet.io.
MTI
Private UK-based IT & cybersecurity company with 214 employees, $45.6M revenue, founded in 1987; specializes in data security, data centre modernization, and IT managed services; provides penetration testing with CREST certification and active testing operations; acquired by Ricoh in 2020.
ResilientX Security
Cybersecurity company specializing in penetration testing, attack surface management, and third-party risk solutions; provides active testing and simulated attack services with a focus on web, cloud, and network security; 10 employees; Founded 2022; London, UK.
Bridewell
Cybersecurity company based in Reading, UK, specializing in computer and network security; 224 employees (+7.9% YoY growth), $6.0M revenue, founded 2013; provides penetration testing and security consulting, trusted by critical infrastructure organizations and highly regulated sectors.
CYFOR Secure | Cyber Security
Cybersecurity company based in Manchester, UK, with $4.1M annual revenue; specializes in penetration testing, digital forensics, incident response, vulnerability assessments, dark web monitoring, and cybersecurity audits; founded in 2002.
Mongoose Cyber Security
UK-based cybersecurity company specializing in CREST-accredited penetration testing; headquartered in Wilmslow, Cheshire, with official registration confirming UK operations; focuses solely on penetration testing services, emphasizing real-world threat simulation.
CyberCX
UK-based cybersecurity company providing penetration testing, incident response, vulnerability assessments, and governance, risk, and compliance services; explicitly signals UK origin and offers detailed pentest solutions.
tmc3
IT services and cybersecurity company based in the United Kingdom; 20 employees with 27.3% YoY growth; founded in 2021; specializes in penetration testing, data protection, security assurance, and secure development lifecycle for government, critical infrastructure, and healthcare sectors.
Cyberfort
UK-based cybersecurity firm specializing in penetration testing services such as code reviews, cloud security testing, AI/LLM testing, and application/web/network/internals testing; performs active attack simulations to identify vulnerabilities.
Methods
UK-based private IT & Services company specializing in digital transformation and cybersecurity; 313 employees, $148.4M revenue, founded 1990, headquartered in London, UK; provides penetration testing services with active engagements and case studies demonstrating expertise.
Wavenet
UK-based IT managed services provider specializing in cybersecurity, communications, and connectivity; offers CHECK & CREST approved penetration testing services; headquartered in Solihull, England, with multiple UK offices; focuses on enhancing security and connectivity for businesses.
Modux
UK-based cybersecurity firm specializing in penetration testing and security assessments; NCSC-approved CHECK company with government accreditation; offers security testing for IT systems, products, and services, with proven expertise in assessing security weaknesses.
Pentest Laboratories
UK-based cybersecurity company founded in 2018; specializes in penetration testing services with modernized methodologies to enhance organizational resilience against cyber threats.
CyberLegion
CyberLegion is a UK-based cybersecurity company specializing in penetration testing, secure-by-design product security, and cybersecurity advisory services; founded in 2021, it has 1 employee and offers crest-approved penetration testing, with a global rank of #6,605,571 and 385 monthly website visits.
Delta Cyber Security Ltd
UK-based cybersecurity company specializing in penetration testing, cyber essentials certification, and cloud security reviews; headquartered in Chichester, West Sussex, with a focus on simplified, accessible security solutions grounded in experience.
Testhouse
UK-based QA and security testing company headquartered in London; offers penetration testing services aligned with OWASP, PCI DSS, and GDPR, recognized by Gartner for quality assurance excellence.
ProCheckUp
ProCheckUp Ltd is a UK-based cybersecurity firm specializing in penetration testing and security audits; CREST-approved and NCSC CHECK accredited, with headquarters in Portsmouth, England, and registered at 14 St Georges Business Centre, Portsmouth, PO1 3EZ.
Acutest
UK-based software testing and quality assurance consultancy; offers penetration testing services; registered in York, England, with additional UK addresses; specializes in testing software, business processes, and IT to improve digital transformation projects.
BT Group
UK-based telecommunications company with 30,295 employees and GBP20.4B annual revenue; operates the largest fixed and mobile networks in the UK; provides active cybersecurity services including penetration testing and ethical hacking; GBP137.8M market cap; over $8.7B in funding; headquartered in London, UK.
Zen Internet
UK-based private telecommunications provider founded in 1995; operates one of the largest independent data networks in the UK; offers broadband, hosting, domains, and security services including penetration testing; 372 employees (+5.8% YoY growth); $109.8M annual revenue; $25.8M funding; B Corp certified; headquartered in Rochdale, UK.
Qualitest
IT services and consulting company specializing in AI-led quality engineering, software testing, and cybersecurity including penetration testing and red team services; 3,735 employees; Founded 1997; London, UK; $220M revenue; Global rank #369,569; 93,202 monthly visits; 3.5/5 employer rating.
BreachLock
Cybersecurity firm based in London, UK, providing penetration testing, attack surface discovery, and red teaming services; offers continuous security testing and evidence-backed attack surface management.
Prolifics Testing
UK-based cybersecurity company specializing in penetration testing; employs CREST-certified professionals; offers internal and external testing for networks, web, mobile, and APIs; registered in the UK with company number 03814910; principal office in Borehamwood, Hertfordshire.
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Rexon Cyber
Cybersecurity company based in London, UK, specializing in penetration testing services; offers internal, wireless, web app, mobile app, cloud, and API pentests, positioning itself as a strategic cybersecurity partner in the UK.
CCL Solutions Group
Cybersecurity and digital forensics company based in the United Kingdom; specializes in penetration testing and breach simulation services, with a focus on identifying security vulnerabilities and protecting digital assets.
KiwiQA
UK-based software testing company specializing in penetration testing; explicitly offers pentest services to reduce security risks, with a UK address at Vista Business Centre, Hounslow, TW4 6JQ. Provides comprehensive QA and testing solutions.
PwC
UK-based professional services firm with 120,836 employees and $55.4B revenue; offers assurance, tax, advisory, and cybersecurity services including penetration testing and ethical hacking (CREST-accredited); registered office at 1 Embankment Place, London; operates globally with a network of over 370,000 staff in 149 countries.
Cybata
Cybata (BD Research Ltd) is a UK-based information services company specializing in cybersecurity, GDPR, and data protection consulting and training for charities and health tech organizations; with 2 employees, 200% YoY growth, and explicitly offers penetration testing services.
Wilbourne
Wilbourne is a UK-based cybersecurity consultancy specializing in bespoke attack simulations, GRC, incident response, and training. With 5 employees and founded in 2018, it provides penetration testing services across web, API, and infrastructure domains, and holds CREST accreditation, demonstrating advanced offensive security capabilities.
CyberPrism
UK-based OT security provider; specializes in operational technology cybersecurity including penetration testing services; registered in London as a Private Limited Company; focuses on safeguarding critical industrial and national infrastructure.
Predatech
UK-based IT services and cybersecurity consultancy specializing in penetration testing, vulnerability management, and security certifications; 8 employees with 28.6% YoY growth since 2020; offers CREST-accredited pentest services and helps organizations enhance cyber defenses.
Netcentrix
UK-based IT managed services provider specializing in cloud, infrastructure, security, and professional services; offers penetration testing services as indicated in their terms and conditions; registered in England with company number 03076196, headquartered in Buckshaw Village, Chorley, Lancashire.
Trustmarque
UK-based IT services and consulting firm founded in 1987; employs 312 staff with $106.5M annual revenue; specializes in IT solutions, cloud, managed, and professional services for healthcare and government sectors. Offers CREST-certified penetration testing services with CHECK accreditation, emphasizing cybersecurity expertise; operates in a competitive landscape including Roke and ECSC Group.
CYSIAM
CYSIAM is a UK-based private cybersecurity firm specializing in threat-led 24/7 Managed Detection and Response (MDR) services; it provides CREST-accredited penetration testing and security consulting, with 29 employees and 13.5% annual growth. The company is trusted by UK public sector organizations and was founded in 2018 in Milton Keynes.
3B Data Security
UK cybersecurity company specializing in incident response, compliance, forensic investigations, and penetration testing; headquartered in Tunbridge Wells with operational address in Sawston, Cambridge; offers penetration testing services and extensive security consulting.
Tranchulas
Cybersecurity company specializing in penetration testing, red teaming, and threat intelligence; 11 employees with 20% YoY growth; founded in 2006; headquartered in London, UK; offers offensive and defensive cyber solutions, ISO 27001, incident response, and cyber training.
Aon
Aon is a private financial services company based in London, UK, with 39,740 employees and $17.0B annual revenue; it offers consulting, risk management, insurance, actuarial, brokerage, and cybersecurity testing services, including CREST-certified penetration testing and red team assessments, demonstrating its comprehensive cyber resilience capabilities.
Air IT Group
UK-based managed IT service provider with 285 employees and $45M revenue; specializes in cybersecurity, business intelligence, and automation for SMEs; CREST-certified for penetration testing, with active pentest services; 21,561 monthly visits, ranked #1,190,653 globally, founded in 2005.
AppCheck Ltd
UK-based cybersecurity firm specializing in automated vulnerability scanning and penetration testing; offers web application and API security assessments, with a focus on continuous, automated testing; markets itself as providing the world's most advanced automated penetration testing tools.
Periculo
UK-based IT services and cybersecurity consultancy with 11 employees, founded in 2015; specializes in cybersecurity for digital health including Penetration Testing, Cyber Essentials, ISO 27001, and Medical Device Security; 18.2% monthly growth, 1,720 monthly visits, ranked #8,134,692 globally.
Evolve North Ltd
UK-based consultancy specializing in Governance, Risk, and Compliance, and IT Security and Assurance; provides penetration testing services to identify and remediate vulnerabilities in IT environments; headquartered in Durham, England, with registered office in North Yorkshire.
Falanx Cyber
Cybersecurity company based in Reading, UK, specializing in penetration testing, cyber defense, and network security solutions; 5 employees with 0% monthly growth and -5.3% YoY decline; founded 2014; serves sectors including public, legal, education, healthcare, and finance; competes with Black Hat, Cyberseer, and Abile Group.
CyberOne
CyberOne (Comtact Ltd.) is a UK-based private cybersecurity firm specializing in proactive security testing, including CREST-accredited penetration testing; 51 employees with +23.4% YoY growth; $12M annual revenue; founded in 2005; offers integrated security solutions such as identity management, email, internet, and network security; recognized as one of 100 global Microsoft partners.
Cyber HQ
Cyber HQ is a cybersecurity consulting company based in the United Kingdom; they provide penetration testing, threat and vulnerability management, security operations, and business resilience services. The firm is registered at 160 City Road, London, with active status and has been operational since at least 2023.
SMARTSEC Information Security
UK-based cybersecurity consultancy founded in 2019 with 3 employees; specializes in penetration testing, Web3 & AI security, security operations, and vCISO advisory; offers comprehensive security solutions and compliance services.
SureCloud
UK-based GRC and risk management software provider; offers penetration testing services including PTaaS with CREST accreditation; headquartered at 1 Sherwood Street, London W1F 7BL, England.
CodeGrazer Ltd.
Cybersecurity firm specializing in penetration testing and security assessments; offers internal penetration testing, web and mobile application security, hardware and IoT hacking, social engineering, and phishing; based in Leeds, UK with 2 employees, founded in 2018.
OnSecurity
UK-based cybersecurity firm specializing in CREST-approved penetration testing; offers AI-augmented services across web, mobile, cloud, and physical security with a focus on efficiency and quality; registered in Bristol, England.
Cybertec.group
UK-based cybersecurity firm specializing in penetration testing; offers CREST-qualified assessments for corporate and government clients, emphasizing integrity and professionalism; over 140 years of experience.
Citation Cyber
Citation Cyber is a UK-based IT services and cybersecurity consulting company with 23 employees and GBP 1.0M annual revenue; founded in 2012 and headquartered in Lancaster, UK. The firm specializes in certified penetration testing, including web, cloud, mobile, and physical assessments, to safeguard systems and data. It competes with Novicom, QSEAP, and Assured, and actively engages in cybersecurity news and awareness campaigns.
Secure Nexus
Secure Nexus is a private UK-based technology and cybersecurity firm founded in 2023, with 2 employees. Specializing in advanced network design, penetration testing, and security solutions, it aims to build a secure digital nexus for clients. Headquartered in Stirling, Scotland, the company focuses on safeguarding digital assets and optimizing connectivity.
Cyber Tech Guardians
Cyber Tech Guardians is a UK-based cybersecurity firm specializing in penetration testing services; headquartered in London with verified address at 3rd Floor/45 Albemarle Street, Mayfair, London W1S 4JL. The company explicitly lists penetration testing as a core service on their website, confirming their role in security assessments.
Secureit
Cybersecurity company headquartered in London, UK; offers penetration testing (pentest) services as a core offering, with UK-based contact info (+44 207 792 5924).
EJN Labs
UK-based private cybersecurity firm specializing in AI-powered cyber defense, including penetration testing, red teaming, and bug bounty; CREST certified; 3 employees; Founded 2022; Headquarters in United Kingdom.
Ethernal
Cybersecurity company specializing in network security, penetration testing, and cyber resilience; founded 2015, 2 employees, based in Highbridge, UK, with 100% monthly growth and services including security health checks, endpoint protection, and compliance.
WhiteHat
Security and investigations company specializing in penetration testing, physical intrusion simulations, and privacy consultancy; UK-based in Preston, with active RED Teaming and privacy counter-measures services.
TIEVA
UK-based IT services and consulting company specializing in transformative business IT solutions, multi-cloud strategies, and cybersecurity, including penetration testing services; 135 employees (+0.6% YoY growth); founded 2007; headquartered in Leeds, UK.
FluidOne
UK-based IT services and consulting firm specializing in secure data, voice, and cloud solutions; offers penetration testing and cybersecurity services; 152 employees, $132.4M revenue, founded 2006, headquartered in London, UK; recognized for high NPS and recent UK expansion.
Tech Guard
Cybersecurity company specializing in computer and network security; provides penetration testing, vulnerability analysis, ethical hacking, ransomware prevention, and social engineering services; 3 employees with 50% YoY growth; founded 2017; based in London, UK.
Cyberhash UK
Cyberhash Limited is a UK-based cybersecurity company specializing in penetration testing services; explicitly offers CREST-certified manual and automated pentests to evaluate defenses against simulated attacks. Registered in England and Wales with an office in Maidenhead.
HZL
Security and investigations company based in the United Kingdom; provides physical penetration testing, red teaming, security training, assessment, and consultancy services. Employs 45 staff with 5.1% YoY growth; founded in 2000. Web presence includes 1,712 monthly visits and a global rank of #8,573,418.
URM
URM (URM Consulting Services Ltd) is a UK-based business consulting firm specializing in information security and risk management; 42 employees with 36.4% YoY growth, $1M-$5M revenue, founded in 2005, headquartered in Reading, UK. The company provides penetration testing, vulnerability assessment, ISO 27001, GDPR, PCI DSS, and business continuity services, with a global rank of #1,589,893 and 14,482 monthly visits.
Astrix
Astrix is a UK-based private cybersecurity firm founded in 1997, with 6 employees and a -16.7% YoY growth. It specializes in computer and network security, explicitly providing penetration testing services as part of its cybersecurity assessments, utilizing questionnaires, automated tools, interviews, and pentests. The company has a modest web presence with 1,208 monthly visits and a global rank of approximately 9.94 million.