Treatwell is seeking a Senior Application Security Engineer to own application security across Product Engineering and to lead the security tooling strategy. You will work hands-on with Java, Spring Boot, Ruby on Rails, TypeScript frontends, and native mobile apps, integrating SAST, DefectDojo, and related workflows across GitLab CI, ArgoCD, and GitHub Actions on AWS/Kubernetes. You will drive threat modelling, ensure secure defaults, triage findings, and present the security posture to senior