Infrastructure Security Engineer

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 , Luig i ), 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 Security
Design and improve isolation mechanisms for multi-tenant workloads (containers, sandboxing, execution environments)

Strengthen boundaries between customers, workloads, and internal systems

Identify and mitigate risks in distributed, dynamic compute environments

Container & Orchestration Security
Secure and harden containerized workloads and orchestration systems (e.g., Kubernetes or similar)

Improve workload isolation, scheduling boundaries, and runtime protections

Evaluate tradeoffs in multi-tenant execution models

Identity & Access Management
Design and improve authentication and authorization systems across services

Implement strong service-to-service identity and least-privilege access patterns

Improve access controls across infrastructure and internal systems

Secrets & Key Management
Build and maintain systems for securely managing secrets, tokens, and credentials

Improve rotation, auditing, and access controls

Reduce secret sprawl and integrate secure patterns into developer workflows

Cloud & Infrastructure Security
Secure cloud environments across providers (AWS, GCP, etc.) with a focus on consistency and portability

Improve network boundaries, service segmentation, and access controls

Embed security into infrastructure-as-code and deployment systems

Engineering Partnership
Work closely with product and infrastructure teams to design secure systems from the ground up

Review architecture and code for security risks and provide actionable guidance

Identify patterns in risks and drive cross-cutting improvements

Requirements:
Core Experience
Experience securing cloud-native infrastructure and distributed systems in production

Background in infrastructure, backend, or security engineering

Experience working in multi-tenant or high-scale environments

Technical Depth
Strong understanding of containerization and orchestration systems (e.g., Kubernetes or similar)

Experience designing or securing isolation mechanisms in multi-tenant systems

Solid understanding of authentication, authorization, and service identity models

Experience with secrets management and secure handling of credentials

Strong foundation in networking concepts (segmentation, service communication, access