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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 MSSPs and companies based in the United Kingdom.
| Company | Category | Based in | Founded | Ownership |
|---|---|---|---|---|
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 |
Bondgate IT Bondgate IT is a managed service provider founded in 1998. | Managed security services | Darlington, United Kingdom | 1998 | 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 |
Corero Network Security Corero Network Security provides automatic DDoS protection for businesses and service providers. | DDoS protection | London, United Kingdom | Public, CNS | |
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 | |
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 | |
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 |
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 |
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 |
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 |
ThreatSpike Red London-based cybersecurity firm offering unlimited, fixed-price penetration testing and red teaming services with ISO 27001 certification and a unique subscription model. | Penetration testing | London, United Kingdom | 2011 | Private |
WorkNest CREST and CHECK-accredited UK penetration testing and managed security provider formed in 2026 from Pentest People, Bulletproof, and Target Defense, with CREST STAR/TLPT-FS capability and the GuardNest vulnerability management platform. | Penetration testing | Chester, United Kingdom | 2014 | Owned by Inflexion |