Infrastructure Security Engineer

About this role

About Us:AI needs a new infrastructure layer. We're building it at Modal.Every era of computing brought new workloads that previous infrastructure couldn't support: mainframes, databases, and the cloud. Each time, the company that rebuilt the layer underneath defined the decade. AI is no different, except it touches everything instead of one slice, and the window to build the layer underneath it is open right now.Our customers include category-defining companies like Lovable, Ramp, Cognition, DoorDash, and Suno. They rely on Modal for instant GPU access, sub-second container starts, and native storage, so it's simple to serve low-latency inference, fine-tune models, and access production-ready sandboxes at scale.We recently raised a $355M Series C at a $4.65B valuation, led by General Catalyst and Redpoint Ventures. We've crossed $300M+ ARR and grown fivefold since September.Our team includes creators of popular open-source projects (e.g.,Seaborn,Luigi), academic researchers, international olympiad medalists, and experienced engineering and product leaders with decades of experience.The Role:We’re looking for an Infrastructure Security Engineer to design and secure the core systems that power our platform. This role focuses on building security directly into our infrastructure—from container isolation and orchestration to identity and secrets management in a multi-tenant, cloud-native environment.You’ll work closely with engineering teams to define secure primitives and ensure our platform is resilient, scalable, and trustworthy by design.This is a hands-on, deeply technical role focused on real systems, not compliance or policy.What You'll Do:Platform & Runtime SecurityDesign and improve isolation mechanisms for multi-tenant workloads (containers, sandboxing, execution environments)Strengthen boundaries between customers, workloads, and internal systemsIdentify and mitigate risks in distributed, dynamic compute environmentsContainer & Orchestration SecuritySecure and harden containerized workloads and orchestration systems (e.g., Kubernetes or similar)Improve workload isolation, scheduling boundaries, and runtime protectionsEvaluate tradeoffs in multi-tenant execution modelsIdentity & Access ManagementDesign and improve authentication and authorization systems across servicesImplement strong service-to-service identity and least-privilege access patternsImprove access controls across infrastructure and internal systemsSecrets & Key ManagementBuild and maintain systems for securely managing secrets, tokens, and credentialsImprove rotation, auditing, and access controlsReduce secret sprawl and integrate secure patterns into developer workflowsCloud & Infrastructure SecuritySecure cloud environments across providers (AWS, GCP, etc.) with a focus on consistency and portabilityImprove network boundaries, service segmentation, and access controlsEmbed security into infrastructure-as-code and deployment systemsEngineering PartnershipWork closely with product and infrastructure teams to design secure systems from the ground upReview architecture and code for security risks and provide actionable guidanceIdentify patterns in risks and drive cross-cutting improvementsRequirements:Core ExperienceExperience securing cloud-native infrastructure and distributed systems in productionBackground in infrastructure, backend, or security engineeringExperience working in multi-tenant or high-scale environmentsTechnical DepthStrong understanding of containerization and orchestration systems (e.g., Kubernetes or similar)Experience designing or securing isolation mechanisms in multi-tenant systemsSolid understanding of authentication, authorization, and service identity modelsExperience with secrets management and secure handling of credentialsStrong foundation in networking concepts (segmentation, service communication, access boundaries)MindsetBuilder mentality, you design and implement, not just reviewPragmatic approach to security in fast-moving environmentsComfortable working deeply with engineers and influencing system designPreferred Qualifications:Experience with sandboxing or runtime isolation technologies (e.g., gVisor, Firecracker, seccomp, or similar)Familiarity with kernel-level or low-level isolation primitivesExperience securing Kubernetes or similar orchestration systems in productionBackground in developer infrastructure, compute platforms, or multi-tenant systems