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Every cybersecurity vendor and service firm on the list. Tick the filters to build a shortlist, then open a profile to see who owns the company and what it does. You can also browse by category or country, or see recent deals.
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See also Cybersecurity consulting firms and companies based in the United Kingdom.
| Company | Category | Based in | Founded | Ownership |
|---|---|---|---|---|
Aardwolf Security Boutique UK penetration testing consultancy in Milton Keynes specialising in manual, expert-led security assessments across web applications, APIs, cloud, and mobile platforms. | Penetration testing | Milton Keynes, United Kingdom | 2015 | Private |
Aon Cyber Solutions Cybersecurity consulting division of global insurance leader Aon, uniquely combining penetration testing with cyber risk quantification and insurance expertise. | Security consulting and vCISO | London, United Kingdom | 2000 | Owned by LevelBlue |
Aristi CHECK and CREST-accredited Birmingham-based cyber security consultancy with over 15 years of experience delivering penetration testing, red teaming, and OT security assessments for government and private sector clients. | Penetration testing | Birmingham, United Kingdom | 2008 | Owned by Limerston Capital |
Automiq Automiq is an automation strategy and transformation partner. | Security consulting and vCISO | London, United Kingdom | 2025 | Private |
Bondgate IT Bondgate IT is a managed service provider founded in 1998. | Managed security services | Darlington, United Kingdom | 1998 | Private |
Bridewell Fast-growing CREST and CHECK-accredited UK cybersecurity consultancy with deep expertise in critical national infrastructure sectors. | Penetration testing | Bristol, United Kingdom | 2013 | Owned by I-TRACING |
BSI Group ISO/IEC 27001 certification audits and information security training from the UK national standards body, which also certifies quality, safety and medical devices. | Compliance audits (SOC 2, ISO 27001) | London, United Kingdom | Private | |
Claranet CREST and CHECK-accredited European managed services provider delivering penetration testing with deep infrastructure and cloud hosting expertise. | Penetration testing | London, United Kingdom | 1996 | Private |
Copper Horse UK security consultancy doing threat modelling, training and research for connected vehicles, IoT and mobile products. | Automotive cybersecurity | Monmouth, United Kingdom | 2011 | Private |
Cyberis CREST and CHECK-accredited UK penetration testing consultancy with CBEST approval, specialising in infrastructure, application, and simulated attack assessments across the public and private sectors. | Penetration testing | Worcester, United Kingdom | 2011 | Owned by Reply |
Cyphere CREST-accredited Manchester-based cyber security firm delivering penetration testing, managed security services, and compliance consultancy across the UK, Europe, and the USA. | Penetration testing | Manchester, United Kingdom | 2020 | Private |
Deloitte Cyber advisory and managed security services, including managed extended detection and response, cloud security, digital identity and threat intelligence, from a global professional services network. | Managed security services | London, United Kingdom | Private | |
Dionach Global enterprise cybersecurity consultancy founded in 1999 in Oxford, holding rare CREST STAR-FS accreditation and delivering penetration testing, red and purple teaming, and PCI QSA services across five international offices. | Penetration testing | Oxford, United Kingdom | 1999 | Owned by Nomios |
Equilibrium Security CREST-accredited Birmingham-based cyber security consultancy delivering penetration testing, social engineering assessments, and Cyber Essentials certification for public and private sector clients. | Penetration testing | Birmingham, United Kingdom | 2012 | Owned by Omni Cyber Security |
Evalian CREST-accredited UK cyber security and data protection consultancy offering penetration testing, ISO consultancy, and managed SOC services from offices across the UK and Ireland. | Penetration testing | Winchester, United Kingdom | 2018 | Private |
EY Cybersecurity consulting and managed services covering security transformation, incident response, data protection and privacy, identity and privileged access, and operational technology security. | Security consulting and vCISO | London, United Kingdom | Private | |
Forefront IT Security Services Forefront IT Security Services presents itself as a virtual cyber security team for organisations in the United Kingdom. | Penetration testing | United Kingdom | 2021 | Private |
GRC Solutions (formerly IT Governance) UK compliance and cybersecurity consultancy, formerly IT Governance, offering CREST and NCSC CHECK penetration testing alongside governance, risk and compliance services. | Penetration testing | Ely, United Kingdom | 2002 | Private |
HORIBA MIRA UK vehicle engineering and test centre offering threat modelling, CSMS support and security testing for vehicles. | Automotive cybersecurity | Nuneaton, United Kingdom | Owned by HORIBA | |
Intertek Testing and certification group that helps vehicle makers and suppliers work towards ISO/SAE 21434 compliance. | Compliance audits (SOC 2, ISO 27001) | United Kingdom | 1885 | Public, ITRK |
Komodo Consulting Israeli-headquartered global cybersecurity consultancy with a UK presence, specialising in penetration testing and TIBER-EU red team exercises for Fortune 500 companies. | Penetration testing | London, United Kingdom | 2011 | Private |
KPMG Cyber security consulting covering strategy and governance, security transformation and cyber threat management, plus cyber managed services and cloud security from member firms. | Security consulting and vCISO | London, United Kingdom | Private | |
Littlefish Littlefish provides managed IT services, cyber security, digital solutions, and data and AI services to organisations. | Managed security services | Nottingham, United Kingdom | 2003 | Owned by Bowmark Capital |
LRQA The only organisation worldwide with a full suite of CREST accreditations. 250+ cybersecurity specialists operating in 55+ countries across pen testing, red teaming, and incident response. | Penetration testing | London, United Kingdom | 1985 | Owned by Goldman Sachs Alternatives |
MDSec Elite UK offensive security consultancy specialising in CBEST/STAR/TIBER red teaming, advanced adversary simulation, and CREST-accredited penetration testing for FTSE 100 clients. | Penetration testing | Southam, United Kingdom | 2011 | Private |
NCC Group Global cybersecurity consultancy with CREST, CHECK, and CBEST accreditation, renowned for deep technical research and penetration testing services. | Penetration testing | Manchester, United Kingdom | 1999 | Public, NCC |
Nethermind Nethermind is a blockchain research, engineering and security company. | Security consulting and vCISO | London, United Kingdom | 2017 | Private |
Pen Test Partners The UK's largest independent security testing firm, renowned for IoT/OT research, CBEST red teaming, and CHECK/CREST-accredited penetration testing across all sectors. | Penetration testing | Buckingham, United Kingdom | 2010 | Private |
PwC Cyber Security Global Big Four professional services firm delivering CREST, CHECK, and CBEST-accredited penetration testing and red teaming services from London, serving the UK's largest enterprises and regulated organisations. | Penetration testing | London, United Kingdom | 1998 | Owned by PwC |
Redscan (A Kroll Business) London-based cybersecurity provider, now part of Kroll, delivering CREST-accredited penetration testing, managed detection and response, and incident response with a 550-strong cyber team. | Penetration testing | London, United Kingdom | 2002 | Part of Kroll |
RedSecLabs CREST-certified and PCI QSA penetration testing consultancy in London, delivering offensive security and compliance services across 25+ countries with research-driven expertise. | Penetration testing | London, United Kingdom | 2023 | Private |
Salus Cyber Award-winning Cheltenham-based cybersecurity consultancy with NCSC CHECK Green Light status and CREST approval, specialising in defence, government, and critical national infrastructure security. | Penetration testing | Cheltenham, United Kingdom | 2017 | Part of LRQA |
SBD Automotive UK automotive consultancy that runs vehicle penetration tests, threat assessments and anti-theft testing for carmakers. | Automotive cybersecurity | Milton Keynes, United Kingdom | Private | |
Secarma Manchester-based independent cybersecurity consultancy with over 20 years of experience delivering CREST and CHECK-accredited penetration testing, red teaming, and compliance certification services. | Penetration testing | Manchester, United Kingdom | 2001 | Private |
SECFORCE UK offensive security consultancy delivering CREST-accredited penetration testing, adversary simulation and CBEST, TIBER-EU and TBEST threat-led testing, mainly for financial services and other large organisations. | Penetration testing | London, United Kingdom | 2008 | Private |
Secvura Secvura reviews web and SaaS applications for security weaknesses and helps teams fix them. | Application security testing | London, United Kingdom | 2026 | Private |
Solusec CREST-accredited UK penetration testing consultancy based in Shropshire, delivering web application, API, infrastructure, cloud, mobile, and AI/LLM testing. A small specialist team, with a retest included in every engagement. | Penetration testing | Albrighton, United Kingdom | 2021 | Private |
Stripe OLT Award-winning CREST-certified managed cyber security and IT support provider with offices in Bristol, London, and Manchester, specialising in penetration testing and Microsoft security technologies. | Penetration testing | Bristol, United Kingdom | 2004 | Part of Littlefish |
System Force IT System Force IT provides managed IT support, cyber security, and Microsoft 365 services to UK SMEs. | Managed security services | Gloucester, United Kingdom | 2006 | Private |