Senior Application Security Engineer

About the Position

Join Capital.com's Product Security team as a Senior Application Security Engineer to enhance application security across the organization.

Locations

• Sofia City, Bulgaria
• Limassol, Cyprus
• Warsaw, Poland

Employment Type

Hybrid

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

Requirements

Experience

• 5+ years in application or product security, or equivalent depth, with a track record of senior or staff-level impact
• Demonstrable experience leading security architecture reviews and threat modelling (e.g. STRIDE, attack trees, data-flow analysis) across multiple teams or products
• Proven 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 submissions
• Strong software engineering ability in at least one language (e.g. Python, Go, JavaScript), with the ability to build automation, not just scripts
• Deep understanding of the OWASP Top Ten, secure design, and secure coding best practices
• Experience with SAST, DAST, SCA, and vulnerability management platforms, and integrating them into CI/CD
• Strong understanding of modern application architectures: REST APIs, microservices, cloud-based systems, and containers
• Practical 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 authority
• A 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 actions
• Experience securing Kubernetes, including cluster hardening, RBAC, network policies, admission control, workload isolation, and image and supply-chain security
• Experience securing AWS infrastructure, including IAM, network and account architecture, key and secret management, and CSPM
• Experience building AI-assisted security tooling or internal self-service security platforms
• Experience mentoring or technically leading a security team
• Offensive or advanced security certifications such as OSAI, OSEP, OSCP, or OSWE

We Offer

• You will join the company, that cares about work and life balance
• Annual Bonus based on the performance review cycle
• Generous Annual Leave Policy
• Medical Insurance and Pension fund, with additional benefit packages based on the location
• Hybrid working model (3 days from our modern office and 2 days fully remotely)
• Comprehensive Workation Policy with 30 more remote days available.
• Possibility 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.

About the Company

Capital.com is a leading global online trading platform, offering a wide range of financial products and services to clients worldwide. We are committed to providing a secure and reliable trading environment, and our Product Security team plays a crucial role in achieving this goal.