Lead and execute web application and API penetration tests as a CHECK Team Leader (App).
Manage end‑to‑end engagements: from scoping and kick‑off sessions through to delivery and client debriefs.
Perform in‑depth manual testing of modern web applications, authentication flows, APIs, and business logic.
Produce clear, detailed, and actionable reports outlining vulnerabilities and tailored remediation guidance.
Stay ahead of emerging application‑level threats and integrate new testing techniques into our methodology.
Automate repetitive tasks and improve efficiency through scripting and tooling enhancements.
Mentor and coach junior testers, particularly around web application testing techniques and report quality.
Enhance application‑focused tools and methodologies, keeping our services current and effective.
Support pre‑sales efforts as a subject‑matter expert in web application security.
Communicate findings effectively to both technical and non‑technical stakeholders.
Contribute to thought leadership through blogs, white papers, or speaking engagements.

CHECK Team Lead (CTL) status – Web Applications.
Current UK SC Clearance.
Minimum 5 years’ penetration testing experience, with a strong focus on web applications and APIs.
Proven experience leading and signing off CHECK web application engagements.
Deep expertise in web application, API, and authentication testing methodologies.
Solid understanding of modern application architectures (cloud-hosted apps, microservices, REST APIs).
Working knowledge of cloud environments (AWS, Azure, GCP) as they relate to application security.
Proficiency with tools such as Burp Suite Pro, along with supporting tooling (e.g. Nmap, Kali).
Strong scripting skills (Python, Shell, etc.).
Excellent communication and technical report‑writing skills.

A discretionary annual performance bonus that rewards your impact and contribution to our success.
Flexible working arrangements and summer hours, because life isn’t 9 to 5, and balance matters.
A highly competitive pension scheme with generous employer contributions, private healthcare, and life assurance for peace of mind.
Employee Assistance Programme, mental health support, cycle-to-work scheme, and regular social events to keep our culture vibrant.
35 days holiday, enhanced maternity pay, and family-first policies so you can focus on what matters most.
From courses to certifications, we’ll invest in your development so you can keep growing and shaping what’s next.
Opportunities to volunteer, give back, and be part of initiatives that make Instil a truly inclusive and connected workplace.

Lead Penetration Tester, CTL App

Key skills