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.
Featured in: Best CREST Pen Testing Companies
About
Pen Test Partners is the largest independent security testing and consultancy business in the United Kingdom, founded in 2010 and headquartered in Buckingham with additional offices in New York. With over 100 UK-based employees, the firm has built an exceptional reputation for deep technical penetration testing, IoT and operational technology security research, and threat-led red teaming under the CBEST, GBEST, STAR-FS, and TIBER frameworks. Their research team regularly discloses vulnerabilities in connected devices, maritime systems, aviation technology, and automotive platforms, making them one of the most publicly visible and research-driven security firms in Europe.
Pen Test Partners holds CHECK, CREST, and CBEST accreditations, alongside PCI QSA qualification, ISO 27001 certification, and Cyber Essentials Plus status. Their penetration testing services cover web applications, APIs, mobile applications, external and internal infrastructure, cloud environments, compiled applications, and source code reviews. Where Pen Test Partners truly differentiates is in their OT, ICS, IIoT, and SCADA security testing capabilities, which include hardware-level assessments of industrial control system devices, PLCs, HMIs, RTUs, and smart instruments.
The firm's CBEST and STAR red teaming services are delivered by CCSAM and CCSAS certified operators who each hold over 14,000 hours of penetration testing experience. Pen Test Partners serves clients across finance, healthcare, retail, transport, energy, and government sectors, and is a recognised supplier on the UK Government's Digital Marketplace.
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