Senior 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 teamsAct 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 workflowsIntegrate and automate security checks across the SDLC and CI/CD pipelines (SAST, DAST, SCA, secrets, and IaC scanning), tuned for strong signal and low frictionOwn and evolve security tooling such as DefectDojo and SAST, DAST, and SCA platforms, maximising automation, coverage, and integrationApply 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 developmentRun vulnerability scans across internal infrastructure and the external perimeter, then analyse findings, define remediation, and track issues to closureSupport and triage the Bug Bounty Program and external vulnerability reports, automating triage where possibleParticipate 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 Requirements: Experience: 5+ years in application or product security, or equivalent depth, with a track record of senior or staff-level impactDemonstrable experience leading security architecture reviews and threat modelling (e.g. STRIDE, attack trees, data-flow analysis) across multiple teams or productsProven ability to automate and scale security processes by building tooling, integrations, and self-service workflows that reduce manual effort Technical: Strong hands-on security testing skills, including code review and web, mobile, and API application security assessments, as well as the ability to triage and validate external vulnerability reports and bug bounty submissionsStrong software engineering ability in at least one language (e.g. Python, Go, JavaScript), with the ability to build automation, not just scriptsDeep understanding of the OWASP Top Ten, secure design, and secure coding best practicesExperience with SAST, DAST, SCA, and vulnerability management platforms, and integrating them into CI/CDStrong understanding of modern application architectures: REST APIs, microservices, cloud-based systems, and containersPractical experience applying AI and LLM tooling to security work, or clear enthusiasm and aptitude to do so Collaboration: Excellent communication and influencing skills: you can explain security concepts to technical and non-technical stakeholders and drive change without direct authorityA self-starter who enjoys solving complex problems, building leverage through automation, mentoring others, and strengthening security culture Nice to have: Experience securing the AI harness: hardening LLM and agent pipelines, prompts, tool and MCP integrations, and model endpoints against prompt injection, data leakage, and insecure agent actionsExperience securing Kubernetes, including cluster hardening, RBAC, network policies, admission control, workload isolation, and image and supply-chain securityExperience securing AWS infrastructure, including IAM, network and account architecture, key and secret management, and CSPMExperience building AI-assisted security tooling or internal self-service security platformsExperience mentoring or technically leading a security teamOffensive or advanced security certifications such as OSAI, OSEP, OSCP, or OSWE What you'll get in return: You will join the company, that cares about work and life balanceAnnual Bonus based on the performance review cycleGenerous Annual Leave PolicyMedical Insurance and Pension fund, with additional benefit packages based on the locationHybrid working model (3 days from our modern office and 2 days fully remotely)Comprehensive Workation Policy with 30 more remote days availablePossibility of taking two additional days of paid leave per year to dedicate to volunteering efforts. We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us.