This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Security Engineer based in United States. This role offers the opportunity to shape and strengthen security practices within a mission-driven technology environment.You will serve as a hands-on security expert, combining strong software engineering skills with deep application and infrastructure security knowledge.The position focuses on embedding security throughout the development lifecycle while partnering with engineering, product, IT, and legal teams.You will help define security strategy, improve technical defenses, and build scalable processes that protect users and systems.This is a highly collaborative role for an engineer who prefers leading through technical execution rather than governance alone.You will have the autonomy to influence architecture, tooling, and security culture while contributing directly to a growing platform used worldwide.