Lead Security Engineer (Application Security)

About us Encord is the universal data layer for AI that helps 300+ AI teams train and run models on the right data. Our platform indexes, curates, annotates, and evaluates data across the full AI lifecycle, from development through production. Trusted by Woven by Toyota, AXA, UiPath, Zipline, and more. We're an ambitious team of 100+ working at the frontier of AI and have raised $60M in Series C funding from Wellington Management, CRV, Next47 and Y Combinator. About the role As Lead Security Engineer, you'll own application security across our platform, embedding secure practices into how we design, build, and ship software, and setting the direction for a growing security function. What you'll do Own the application security program end to end: threat modelling, secure design reviews, code review, and vulnerability management. Build security into the SDLC with SAST, DAST, dependency/SCA, and secrets scanning integrated into CI/CD without slowing teams down. Partner with engineering on authentication, authorization, multi-tenancy isolation, and data protection across our APIs and SDKs. Lead penetration testing, bug bounty triage, and incident response for application-layer issues. Support customer security reviews and compliance (SOC 2, HIPAA, GDPR) with practical technical controls. Mentor engineers and raise the security bar across the organisation. What we're looking for 7+ years in software or security engineering, with significant hands-on AppSec experience. Strong coding ability (Python and/or TypeScript ideal) and the credibility to review and fix code, not just flag issues. Deep knowledge of web and API security (OWASP Top 10, OAuth/OIDC, authz models, SSRF, injection, deserialisation). Experience securing cloud-native SaaS (GCP or AWS, Kubernetes, containers). Track record of building security tooling and processes in a fast-moving product company. Clear communicator who can influence engineering teams and speak to enterprise customers. Nice to have Experience with ML/AI systems security (data pipelines, model supply chain, LLM-specific risks such as prompt injection). Background in regulated industries such as healthcare. Previous experience as an early or first dedicated security hire. Why Encord Competitive salary, and meaningful equity in a high-growth startup Strong in-person culture — most of the team works from our London office 4+ days/week 25 days annual leave + UK public holidays Annual learning & development budget Travel for customer visits, events, and conferences across the UK and Europe Daily company lunches Monthly socials & bi-annual team offsites Operating principles High agency You see something broken, you fix it or find the person who can. We celebrate the people who solve 90% of a problem before anyone asks. Build with care & urgency We bear-hug the customer. Former founders and people from fast-moving, high-stakes environments thrive here. Self-aware & hungry We stay warm, self-aware, and genuinely hungry. We elevate our peers, and ego doesn't last long. Invent in real time We move toward the ambiguity. We’re pragmatic, resourceful, energized by the fact that there's no playbook. If you're looking to do the most meaningful work of your career alongside people who push you to be better, we'd love to meet you.