Software Security Engineer, Secure Frameworks

About the role

You will design, build and run security foundations used across Anthropic's fleet, from threat model through production, on-call and adoption. Much of the work is greenfield: our infrastructure is growing quickly and the timelines are compressed, so you will help define the architecture rather than inherit it. Depending on your strengths you will focus on one or two of the areas below and contribute across the rest.

• Build critical security foundations including cryptographic frameworks, mTLS infrastructure, secure serialization, and authorization systems, designed to prevent entire classes of vulnerabilities
• Partner with product, research, infrastructure, and other security teams to ensure frameworks integrate smoothly with lower-layer security controls
• Scope, design and build security services and libraries end-to-end, maintain them in production, and drive through ambiguous technical problems with minimal oversight
• Build and operate the zero-trust access gateway that fronts Anthropic's internal services
• Design and roll out authorization frameworks so services enforce least privilege consistently instead of each inventing its own access controls
• Own cryptographic frameworks and libraries
• Mentor engineers, contribute to hiring, and grow security engineering culture across Anthropic

Minimum qualifications

• 8+ years of software engineering experience building security-relevant systems in production, including leading complex initiatives independently
• Strong programming skills in Go, Rust or Python
• Deep understanding of authentication and authorization systems: OAuth 2.0 / OIDC, JWTs, service-to-service auth, policy-based access control
• Hands-on experience with PKI, X.509, mTLS and workload identity
• Working knowledge of applied cryptography: choosing and composing primitives correctly, key management, and the ways libraries fail in practice
• Experience shipping and operating high-reliability services on Kubernetes across cloud and on-prem environments, including being on call for them
• A track record of bringing clarity and ownership to ambiguous technical problems and driving them to resolution across teams
• A strong sense of developer experience
• Clear communication across all levels of the organization
• Passion for AI safety and the role security engineering plays in building trustworthy AI systems

Preferred qualifications

• Built security frameworks or libraries adopted across an engineering organization, and done the work to drive that adoption
• Built or operated a zero-trust / BeyondCorp-style access gateway or identity-aware proxy
• Migrated a fleet to mTLS at scale, including certificate issuance and staged enforcement
• Maintained or contributed to open-source cryptographic libraries
• Designed authorization systems using policy languages or relationship-based models
• Familiarity with ML infrastructure (training, inference serving)