Application Security Engineering Manager

Synthesia is the world’s leading AI video platform for business, used by over 90% of the Fortune 100. Founded in 2017, the company is headquartered in London, with offices and teams across Europe and the US. As AI continues to shape the way we live and work, Synthesia develops products to enhance visual communication and enterprise skill development, helping people work better and stay at the center of successful organizations. Following our recent Series E funding round, where we raised $200 million, our valuation stands at $4 billion. Our total funding exceeds $530 million from premier investors including Accel, NVentures (Nvidia's VC arm), Kleiner Perkins, GV, and Evantic Capital, alongside the founders and operators of Stripe, Datadog, Miro, and Webflow. Location: Europe remote or London hybrid ABOUT THE ROLE: As our engineering and research organisation grows, so does the complexity of securing it. Our Application Security team is at the forefront of that challenge — building AI-native security tooling, embedding security into the development lifecycle at scale, and finding ways to make a small, highly capable team punch well above its weight. We're looking for an Engineering Manager to lead and grow the AppSec team. This is not a coordination role. You'll be leading a team of exceptionally senior and staff-level engineers who are deeply self-directed and technically excellent. To earn their trust and enable their best work, you'll need to be genuinely close to the craft — able to engage at depth on threat modelling, agentic security tooling, SDLC design, and application risk. You'll also own AppSec strategy and be accountable for how the function scales alongside a product organisation that is growing fast and leaning heavily into AI-assisted development. Important note: Anyone working as a manager within the Infosec team will need to follow the Infosec Team Management Tenets https://www.linkedin.com/posts/tschammer_celebrating-2-years-at-synthesia-its-activity-7171085109989765121-5kaN/. KEY RESPONSIBILITIES: - Lead, support, enable and grow the AppSec team — owning hiring, onboarding, performance, and career development for a team of Senior and Staff-level Security Engineers. Important to understand: we're not looking for someone to dictate the roadmap or daily activities of the team. What we need is someone to enable the team to do what needs doing and to give them the best possible environment to do it in. - Own the formalisation of AppSec strategy and roadmap, translating team input, business risk and engineering context into a clear, prioritised programme of work with measurable outcomes. - Be a credible technical partner to your team — able to engage substantively on threat models, security architecture, agentic tooling design, and risk decisions, and willing to get into the details when it matters. - Define and maintain the team's operating rhythm: OKRs, quarterly planning, cross-team coordination, and stakeholder communication up to leadership. - Act as a key interface between AppSec and the rest of the organisation and leadership — building relationships with business leadership, engineering leads, the Developer Platform team, Architecture Working Group, and partner functions like Legal and Moderation, to embed security into how Synthesia builds. - Participate in maintaining and evolving Synthesia's approach to AI-assisted development security, including how we secure our own use of agentic coding tools and how we assess the security of AI-generated code. - Own AppSec's relationship with the broader Security function, ensuring tight alignment between AppSec and other Infosec teams on shared risks, incidents, and cross-cutting initiatives. - Represent AppSec externally where relevant — with customers, auditors, and in the context of compliance programmes such as SOC2 and ISO42001. WHAT'S IN IT FOR YOU: - Lead a small, senior team with high autonomy, and focus on creating leverage rather than running a ticket queu