UK penetration testing companies

London-based consultancy offering CREST-accredited penetration testing, incident response and PCI compliance.

UK penetration testing firm holding CREST accreditation, known for cloud and application security testing.

UK offensive security firm offering CREST-accredited penetration testing and financial-sector threat-led testing (STAR-FS).

UK cyber security and data protection consultancy holding CREST accreditation for penetration testing.

UK cyber security consultancy offering CREST-accredited penetration testing, threat-led testing, managed detection and response.

UK cyber security provider offering CREST-accredited penetration testing and compliance services.

UK-based cyber security firm (with UAE and US offices) offering CREST-accredited penetration testing.

UK cyber security provider, now trading as CNS at Six Degrees, listed on the CREST Marketplace for penetration testing and on the NCSC CHECK register as 6 Degrees Holdings Ltd.

UK cyber security firm offering CREST-accredited penetration testing including web and mobile application testing.

UK offensive security firm offering CREST-accredited continuous red teaming and penetration testing on a subscription model.

UK cyber security group offering CREST-accredited penetration testing, incident response and secure hosting.

UK consultancy offering CREST-accredited penetration testing and security risk management.

UK penetration testing firm offering CREST-accredited infrastructure and web application testing and Cyber Essentials certification.

UK consultancy offering CREST-accredited penetration testing, incident response and information security auditing.

Ireland-based provider (serving the UK) delivering CREST-accredited penetration testing and continuous vulnerability management via a PTaaS platform.

UK penetration testing firm holding CREST accreditation and Cyber Essentials Plus.

UK-headquartered global firm offering CREST-accredited penetration testing, digital forensics and PCI compliance services.

UK boutique penetration testing firm holding CREST accreditation and Cyber Essentials Plus.

UK cyber security specialist offering CREST-accredited penetration testing, social engineering, cloud reviews and wireless auditing.

UK cyber security consultancy offering CREST-accredited penetration testing, threat-led testing and managed detection services.

UK boutique security firm holding CREST accreditation for penetration testing.

UK security firm holding CREST accreditation for penetration testing.

UK consultancy specialising in CREST-accredited penetration testing and financial-sector threat-led testing (CBEST, GBEST, TIBER-EU).

UK security firm holding CREST accreditation for penetration testing.

Long-established UK consultancy offering CREST-accredited penetration testing, vulnerability assessment and incident response.

UK offensive security consultancy (formerly WithSecure Consulting) offering CREST-accredited penetration testing and threat-led testing (CBEST, GBEST, TIBER-EU).

UK firm providing CREST-accredited penetration testing alongside the Rootshell vulnerability-management platform.

UK penetration testing provider holding CREST accreditation for penetration testing services.

Cheltenham-based cyber security firm offering CREST-accredited penetration testing.

UK cyber security consultancy offering CREST-accredited penetration testing and vulnerability assessment.

UK information security consultancy providing CREST-accredited penetration testing and Cyber Essentials certification.

Exeter-based cyber security firm holding CREST accreditation for penetration testing.

UK security firm offering CREST-accredited penetration testing and security certification training.

Cyber division of Thomas Murray offering CREST-accredited penetration testing and incident response.

Penetration testing firm listed on the CREST Marketplace as Truststream Cybersecurity Limited, part of SysGroup. CREST links to the SysGroup website.

Cambridge-based cyber security firm offering CREST-accredited penetration testing and managed security services.

Penetration testing provider that traded as Pentest People until 2025 and is now part of WorkNest, listed under WorkNest on the NCSC CHECK register and the CREST Marketplace.