Independent directory
UK penetration testing companies
Compare 52 UK providers by accreditation, service, and size. Firms are listed from public sources, such as the CREST Marketplace, the NCSC CHECK list and company sites, with the source linked on each listing.
2-sec Consulting
London · Small (11–50)
London-based consultancy offering CREST-accredited penetration testing, incident response and PCI compliance.
4ARMED Ltd
Boutique (1–10)
UK penetration testing firm holding CREST accreditation, known for cloud and application security testing.
AmberWolf
Small (11–50)
UK offensive security firm offering CREST-accredited penetration testing and financial-sector threat-led testing (STAR-FS).
Arcanum Cyber
Mid-size (51–200)
UK cyber security consultancy offering CREST-accredited penetration testing and security consultancy.
Avord Ltd
Small (11–50)
UK provider delivering CREST-accredited penetration testing through an online security-testing platform.
Blackfoot UK Ltd
Small (11–50)
UK cyber security and data protection consultancy holding CREST accreditation for penetration testing.
Bridewell
Large (201–1000)
UK cyber security consultancy offering CREST-accredited penetration testing, threat-led testing, managed detection and response.
Citation Cyber
Small (11–50)
UK cyber security provider offering CREST-accredited penetration testing and compliance services.
Claranet Cyber Security
Large (201–1000)
Cyber security division of Claranet providing CREST-accredited penetration testing, application testing and managed security services.
Closed Door Security Ltd
Small (11–50)
UK-based cyber security firm (with UAE and US offices) offering CREST-accredited penetration testing.
CNS Group (now part of Six Degrees)
Large (201–1000)
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.
Cognisys Group Ltd
Mid-size (51–200)
UK cyber security firm offering CREST-accredited penetration testing including web and mobile application testing.
CovertSwarm
Mid-size (51–200)
UK offensive security firm offering CREST-accredited continuous red teaming and penetration testing on a subscription model.
CyberCrowd
Small (11–50)
UK information risk and cyber security provider offering CREST-accredited penetration testing.
Cyberfort Limited
Large (201–1000)
UK cyber security group offering CREST-accredited penetration testing, incident response and secure hosting.
Cyberis Reply Ltd
Small (11–50)
UK consultancy (part of Reply) offering CREST-accredited penetration testing and financial-sector threat-led testing (STAR-FS).
Cynance Consulting Ltd
Boutique (1–10)
UK consultancy offering CREST-accredited penetration testing and security risk management.
Cyphere
Boutique (1–10)
UK penetration testing firm offering CREST-accredited infrastructure and web application testing and Cyber Essentials certification.
D2 Network Associates Ltd
Small (11–50)
UK IT and cyber security firm offering CREST-accredited penetration testing and managed security services.
Dionach Ltd
Mid-size (51–200)
UK consultancy offering CREST-accredited penetration testing, incident response and information security auditing.
edgescan (BCC Risk Advisory Ltd)
Large (201–1000)
Ireland-based provider (serving the UK) delivering CREST-accredited penetration testing and continuous vulnerability management via a PTaaS platform.
Exosec Ltd
Boutique (1–10)
UK penetration testing firm holding CREST accreditation and Cyber Essentials Plus.
Foregenix Ltd
Large (201–1000)
UK-headquartered global firm offering CREST-accredited penetration testing, digital forensics and PCI compliance services.
Fortbridge
Boutique (1–10)
UK boutique penetration testing firm holding CREST accreditation and Cyber Essentials Plus.
Illume
Boutique (1–10)
UK cyber security specialist offering CREST-accredited penetration testing, social engineering, cloud reviews and wireless auditing.
Intruder
Mid-size (51–200)
UK vulnerability-management and attack-surface monitoring platform with CREST-accredited vulnerability assessment and PTaaS offering.
IOActive Inc
Seattle · Large (201–1000)
Research-led security firm with a UK CREST-accredited entity offering penetration testing and hardware/embedded security assessment.
JUMPSEC Ltd
Small (11–50)
UK cyber security consultancy offering CREST-accredited penetration testing, threat-led testing and managed detection services.
Laneden Ltd
Boutique (1–10)
UK boutique security firm holding CREST accreditation for penetration testing.
Leo CybSec
Boutique (1–10)
UK cyber security consultancy holding CREST accreditation for penetration testing.
Liora Security Solutions Limited
Boutique (1–10)
UK security firm holding CREST accreditation for penetration testing.
MDSec Consulting Ltd
Mid-size (51–200)
UK consultancy specialising in CREST-accredited penetration testing and financial-sector threat-led testing (CBEST, GBEST, TIBER-EU).
Mobius Binary Limited
Small (11–50)
UK security firm holding CREST accreditation for penetration testing.
NCC Group
Manchester · Enterprise (1000+)
UK-headquartered global cyber security firm providing CREST-accredited penetration testing, threat-led testing, incident response and threat intelligence.
ONSecurity Technology Limited
Mid-size (51–200)
UK provider delivering CREST-accredited penetration testing through a subscription-based online platform.
Orange Cyberdefense
Large (201–1000)
UK arm of the international Orange Cyberdefense group offering CREST-accredited penetration testing and managed security.
Pen Test Partners
Size not stated
UK consultancy offering CREST-accredited penetration testing across web, mobile, infrastructure and specialist areas such as maritime, automotive and aviation.
Pentest Cyber
Boutique (1–10)
UK penetration testing firm holding CREST accreditation and Cyber Essentials Plus.
Prism Infosec Ltd
Cheltenham · Small (11–50)
Cheltenham-based consultancy offering CREST-accredited penetration testing and financial-sector threat-led testing (STAR-FS).
ProCheckUp Ltd
Small (11–50)
Long-established UK consultancy offering CREST-accredited penetration testing, vulnerability assessment and incident response.
Reversec
Large (201–1000)
UK offensive security consultancy (formerly WithSecure Consulting) offering CREST-accredited penetration testing and threat-led testing (CBEST, GBEST, TIBER-EU).
Rootshell Security Ltd
Mid-size (51–200)
UK firm providing CREST-accredited penetration testing alongside the Rootshell vulnerability-management platform.
Ruptura InfoSecurity
Small (11–50)
UK penetration testing provider holding CREST accreditation for penetration testing services.
Salus Digital Security Ltd (SalusCyber)
Cheltenham · Small (11–50)
Cheltenham-based cyber security firm offering CREST-accredited penetration testing.
Secarma Ltd
Small (11–50)
UK cyber security consultancy offering CREST-accredited penetration testing and vulnerability assessment.
SecQuest Information Security Ltd
Small (11–50)
UK information security consultancy providing CREST-accredited penetration testing and Cyber Essentials certification.
Securious Limited
Exeter · Small (11–50)
Exeter-based cyber security firm holding CREST accreditation for penetration testing.
The SecOps Group
Boutique (1–10)
UK security firm offering CREST-accredited penetration testing and security certification training.
Thomas Murray Cyber Limited
Small (11–50)
Cyber division of Thomas Murray offering CREST-accredited penetration testing and incident response.
Truststream Cybersecurity Limited
Large (201–1000)
Penetration testing firm listed on the CREST Marketplace as Truststream Cybersecurity Limited, part of SysGroup. CREST links to the SysGroup website.
UK Cyber Defence Ltd
Cambridge · Small (11–50)
Cambridge-based cyber security firm offering CREST-accredited penetration testing and managed security services.
WorkNest Secure (formerly Pentest People)
Size not stated
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.