Security engineer, application security (UK)

Neura Market; Greater London; Hybrid; GBP 90,000 - 135,000; Full time

Benefits offered by this job

Generous PTO

Health insurance

Parental leave

Fertility support

Pension scheme

Wellness stipend

Learning and development stipend

Company off-sites

Stock options

Job summary

WRITER in London is seeking a security engineer to build the security foundations for our AI-powered platform. You will work at the intersection of application security, AI infrastructure, and developer enablement—embedding security into code from day one.

You will tackle threat modeling, automated controls, secure coding standards, and secure data pipelines, balancing risk with velocity while reporting to the head of security engineering in a hybrid London setup.

Qualifications

• 4+ years of hands-on experience in application security engineering.
• Understanding of developer workflows for shipping features with risk balance.
• Proficiency in at least two programming languages (Python, Java, Go, JS/TS).
• Knowledge of SAST/DAST, vulnerability management, security testing frameworks, and DevSecOps practices.
• Excellent communication to translate security concepts for technical and non-technical audiences.
• Builder's mindset to automate, scale, and empower, not bottleneck.
• Alignment with WRITER values: Connect, Challenge, Own.

Responsibilities

• Build security into the DNA of our AI platform through threat modeling with product teams and secure architectures.
• Own and evolve our application security program, including CI/CD scanning, security code reviews, and automation to catch vulnerabilities before production.
• Champion secure coding standards and create reusable security patterns and libraries for developers.
• Design and recommend security features to protect customer environments and data pipelines.
• Integrate AI agents to increase velocity for security and engineering teams while reducing risk.
• Lead security assessments and penetration testing of applications, AI services, and APIs, remediating issues at scale.
• Design and implement controls for data pipelines, model training environments, and customer-facing agents.
• Stay ahead of AI/ML security threats and actively build defenses against novel risks.

Skills

Application security

Threat modeling

CI/CD security

Security code reviews

Secure coding standards

Automation minded

Communication skills

Tools

SAST/DAST tools

Vulnerability management

Security testing frameworks

DevSecOps

Job description

About WRITER

WRITER is where the world's leading enterprises orchestrate AI-powered work. Our vision is to expand human capacity through superintelligence. And we're proving it's possible – through powerful, trustworthy AI that unites IT and business teams together to unlock enterprise-wide transformation. With WRITER's end-to-end platform, hundreds of companies like Mars, Marriott, Uber, and Vanguard are building and deploying AI agents that are grounded in their company's data and fueled by WRITER's enterprise-grade LLMs. Valued at $1.9B and backed by industry-leading investors including Premji Invest, Radical Ventures, and ICONIQ Growth, WRITER is rapidly cementing its position as the leader in enterprise generative AI.

Founded in 2020 with office hubs in San Francisco, New York City, Seattle, Austin, Chicago, and London, our team thinks big and moves fast, and we're looking for smart, hardworking builders and scalers to join us on our journey to create a better future of work with AI.

About the role

This is where security meets innovation at enterprise scale. As a security engineer, applications at WRITER, you'll be building the security foundations that protect the AI systems powering some of the world's most recognizable brands. You'll work at the intersection of application security, AI infrastructure, and developer enablement—partnering with engineering teams to embed security into every line of code while ensuring our platform remains both powerful and trustworthy.

The opportunity is massive: you'll help define how enterprise AI applications are secured, from threat modeling our LLM architectures to building automated security controls that scale across our growing platform. This isn't about saying "no"—it's about finding creative ways to say "yes, and here's how we do it securely." You'll tackle challenges that most security engineers never encounter: securing AI agents, protecting training data pipelines, and designing controls for systems that didn't exist a few years ago.

This role is hybrid from our London office, reporting to the head of security engineering.

What you'll do

• Build security into the DNA of our AI platform by conducting threat modeling sessions with product teams, designing secure architectures for new features, and ensuring security considerations shape product decisions from day one—not after the fact

• Own and evolve our application security program including establish and maintain SAST/DAST scanning in CI/CD pipelines, conducting security code reviews for critical changes, and building automation that catches vulnerabilities before they reach production

• Partner with engineering teams to establish and champion secure coding standards, creating reusable security patterns and libraries that make it easier for developers to build securely by default

• Design and recommend security features and products that help secure customer environments. You are the advocate and the vision for how we protect and secure customers..

• Integrate and leverage AI agents to help increase velocity for the security team and the overarching engineering org to ensure that we are proactive in minimizing risk while we build products

• Lead security assessments and penetration testing of WRITER's applications, AI services, and APIs, identifying vulnerabilities across our tech stack and working collaboratively with teams to remediate issues at scale

• Design and implement security controls for protecting data pipelines, model training environments, and customer-facing AI agents

• Stay ahead of emerging threats in the AI/ML security landscape, researching attack vectors specific to LLMs and generative AI, and proactively building defenses against novel risks

What you need

• 4+ years of hands-on experience in application security engineering, with a proven track record of securing large-scale production systems—bonus points if you've worked in fast-growing startups or high-growth environments

• Understanding of developer experience and developer workflows for shipping features and products. You care deeply about reducing risk while considering velocity of engineers.

• Technical expertise in at least two programming languages (Python, Java, Go, JavaScript/TypeScript) and the ability to read and review code across multiple languages, understanding both business logic and security implications

• Knowledge of security tools and methodologies including SAST/DAST solutions, vulnerability management platforms, security testing frameworks, and DevSecOps practices—you know which tools to use and when automation beats manual review

• Excellent communication skills that allow you to translate complex security concepts into clear recommendations for both technical and non-technical audiences—you can explain why something matters and motivate teams to action

• A builder's mindset that looks for opportunities to automate, scale, and empower rather than create bottlenecks—you understand that security enables the business, not blocks it

• Alignment with WRITER's values of Connect (building strong relationships across teams), Challenge (pushing the boundaries of what's possible in AI security), and Own (taking end-to-end responsibility for the security of our platform)

  Benefits & perks (UK full-time employees):

  • Generous PTO, plus company holidays

  • Comprehensive medical and dental insurance

  • Paid parental leave for all parents (16 weeks)

  • Fertility and family planning support

  • Early-detection cancer testing through Galleri

  • Competitive pension scheme and company contribution

  • Annual work-life stipends for:

    • Wellness stipend for gym, massage/chiropractor, personal training, etc.

    • Learning and development stipend

  • Company-wide off-sites and team off-sites

  • Competitive compensation and company stock options