Application Security Engineer

Capital.com's Product Security team protects our web and mobile applications, infrastructure, and external perimeter in a highly regulated environment. As Senior/Staff Application Security Engineer, you will raise the bar for application security across the organisation. This role is measured by leverage: how well you design, automate, and scale security processes so that many engineering teams can build securely by default.

You will lead security architecture reviews and threat modelling, increasingly with the help of AI tooling, and turn one-off security work into repeatable, self-service capabilities. The role combines deep hands-on offensive and defensive security expertise with the engineering mindset needed to automate at scale. You will work closely with development, QA, DevOps, and platform teams.

Responsibilities:

Security Architecture & Threat Modelling:

• Lead security architecture reviews and threat modelling for new and existing systems, using AI tools to make reviews faster, more consistent, and scalable across teams
• Act as a security force multiplier by influencing the standards, patterns, and guardrails that let teams move fast and stay secure

Security Automation & Tooling:

• Design, build, and automate scalable security processes that engineering teams can self-serve, covering secure design review, threat modelling, testing, and remediation workflows
• Integrate and automate security checks across the SDLC and CI/CD pipelines (SAST, DAST, SCA, secrets, and IaC scanning), tuned for strong signal and low friction
• Own and evolve security tooling such as DefectDojo and SAST, DAST, and SCA platforms, maximising automation, coverage, and integration
• Apply AI and LLM-based tooling to architecture review, threat modelling, code review, and vulnerability triage, and help define how the team adopts these tools safely

Security Testing & Vulnerability Management:

• Conduct and oversee security assessments of web and mobile applications, APIs, and cloud infrastructure, including manual testing and PoC development
• Run vulnerability scans across internal infrastructure and the external perimeter, then analyse findings, define remediation, and track issues to closure
• Support and triage the Bug Bounty Program and external vulnerability reports, automating triage where possible
• Participate in and help lead red teaming and offensive security exercises

Enablement:

• Drive knowledge sharing on secure development, mentor engineers, and deliver training for development and QA teams