Senior Offensive Security Engineer New Cardiff, London or Remote (UK)

Monzo’s Offensive Security team is looking for a security professional to identify and demonstrate vulnerabilities before others do through testing, red teaming, purple teaming, and adversarial research.

Responsibilities

• Leading offensive security projects from initial idea through to execution and reporting
• Simulating real‑world attacks to uncover vulnerabilities across our systems, infrastructure, and products
• Partnering with engineering and security teams to improve detection, response, and resilience
• Bringing an attacker mindset into conversations – asking what if? and challenging assumptions
• Producing proof‑of‑concept exploits to clearly demonstrate risk and drive meaningful fixes
• Mentoring others in the team and acting as a highly independent technical lead on complex engagements

Qualifications

• Strong attacker mindset and natural curiosity about how systems can be broken
• Hands‑on experience in offensive security across areas such as web, mobile, cloud, or infrastructure
• Comfortable working across modern tech stacks (e.g., Kubernetes, AWS/GCP, microservices) or excited to learn
• Ability to take ownership of ambiguous problems and drive them through to impactful outcomes
• Enjoys collaborating with others and influencing teams to think more securely
• Experienced in security testing and/or holding relevant certifications (e.g., OSCP, CREST)

Benefits

• £76,500 – £90,000 salary plus performance‑based incentive awards
• Role can be based in London office or work remotely within the UK with occasional meetings in London
• Flexible working hours with trust to work the hours necessary for quality results
• £1,000 annual learning budget for books, training courses, and conferences
• Work‑from‑home setup support, with all employees receiving MacBooks and additional support for fully remote workers
• Additional benefits available – full list in our benefits page

Equal opportunities

We’re an equal opportunity employer. All applicants will be considered for employment without attention to age, ethnicity, religion, sex, sexual orientation, gender identity, family or parental status, national origin, or veteran, neurodiversity or disability status.

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