Security Engineer, Application Security (UK)

Location: Hybrid from the London office, United Kingdom

Company

Writer is an AI platform for enterprise marketing and revenue teams, using autonomous agents and governed enterprise knowledge to support growth.

What you will do

• Conduct threat modeling with product teams and design secure architectures for AI platform features.
• Own and evolve the application security program, including SAST/DAST in CI/CD, critical code reviews, vulnerability automation, and secure coding standards.
• Partner with engineering teams to create reusable security patterns and libraries that support secure-by-default development.
• Design security features and controls for customer environments, data pipelines, model training environments, and customer-facing AI agents.
• Lead security assessments and penetration testing across applications, AI services, and APIs, coordinating remediation at scale.
• Research LLM and generative AI attack vectors and use AI agents to improve security team and engineering velocity.

Requirements

• 4+ years of hands-on application security engineering experience, including securing large-scale production systems.
• Understanding of developer experience and workflows for shipping features while balancing security risk and engineering velocity.
• Technical expertise in at least two of Python, Java, Go, and JavaScript/TypeScript, with the ability to review code across multiple languages.
• Knowledge of SAST/DAST, vulnerability management platforms, security testing frameworks, and DevSecOps practices.
• Excellent communication skills for explaining security concepts to technical and non-technical audiences and motivating teams to act.
• A builder’s mindset focused on automation, scalability, and enabling rather than blocking the business.
• Alignment with Writer’s values: Connect, Challenge, and Own.

Nice to have

• Experience in fast-growing startups or high-growth environments.

Culture & Benefits

• Full-time employment with hybrid work from the London office.
• Generous paid time off and company holidays.
• Medical and dental insurance, paid parental leave of 16 weeks for all parents, and fertility and family planning support.
• Competitive pension scheme with company contribution.
• Wellness and learning and development stipends.
• Company and team off-sites, competitive compensation, and stock options.