Infrastructure Security Engineer

About Antithesis We've been quietly reinventing how the world thinks about software reliability, and we're just getting started! At Antithesis, we start at the foundations – we run entire software systems inside a deterministic simulation and break them in every way imaginable. Every issue then comes with a perfect reproduction, so you can identify root causes fast instead of spending days trying to recreate what went wrong. The rise of AI-generated code has made this work more urgent than ever. Agents can write code faster than any human, but speed doesn't matter much when the output is buggy, stuck in review, or slipping through undetected. The verification bottleneck is real, it's growing, and solving it is one of the most consequential problems in software right now. That's what you'd be working on. We're well-funded and deeply technical, the kind of place where the hardest problems get the most attention and the best ideas win regardless of who has them. If you want to do work that actually moves the needle on how reliable software can be, keep reading. About the Role Antithesis is growing and seeking an experienced Infrastructure & Security Engineer to join our Platform team, which owns the infrastructure, services and tools used to build, deploy and operate the Antithesis services & products. We strive to act as a productivity accelerator by providing secure, scalable infrastructure primitives that enable engineering teams to move fast without compromising security or reliability. In this role, you will design, build, and scale secure cloud infrastructure that powers Antithesis’ core systems and customer environments. You’ll operate at the intersection of infrastructure, security, and reliability—ensuring our cloud environments are resilient, isolated, observable, and secure by default. As our systems grow in complexity and scale, the security and isolation of our cloud infrastructure become increasingly critical. You’ll help define and implement the technical foundations that protect our systems, customers, and data. What You’ll Do Cloud Infrastructure & Architecture Design, build, and operate secure, scalable cloud infrastructure across compute, networking, and storage Architect multi-tenant and isolated cloud environments with strong security boundaries Lead capacity planning and scaling initiatives to support rapid product and customer growth Make critical architectural decisions balancing performance, cost, reliability, and security Network Security & Isolation Design and implement network segmentation, private networking, and zero-trust principles Build and maintain secure VPC architectures, ingress/egress controls, and service-to-service communication policies Implement tenant isolation strategies across infrastructure and workloads Conduct threat modeling and proactively reduce infrastructure attack surface Identity, Access & Data Security Build and maintain authentication and authorization frameworks across internal systems Implement audit logging, access monitoring, and compliance-aligned controls Manage secrets, key management systems, and secure credential workflows Automation & Platform Enablement Establish infrastructure-as-code standards and automation best practices Build tooling and paved paths that improve developer productivity and security posture Contribute to long-term infrastructure roadmap and technical strategy Mentor engineers on infrastructure and security best practices What We’re Looking For We’re looking for engineers who thrive at the intersection of cloud infrastructure, security engineering, and distributed systems . You likely have: 5+ years of experience in infrastructure, platform, or security engineering Deep experience with cloud providers (AWS, GCP, or Azure) Strong knowledge of cloud networking concepts (VPCs, subnets, routing, firewalls, load balancing) Experience implementing IAM, RBAC, and least-privilege access models at scale Hands-on experience with Infrastructure-as-Code tools (Terraform, Pulumi, CloudFormation, etc.) Experience designing highly available, fault-tolerant systems Understanding of security best practices across cloud infrastructure Bonus if you have: Experience in high-growth or multi-tenant SaaS environments Background in security engineering or compliance frameworks (SOC 2, ISO 27001, etc.) Experience with secrets management, KMS, or certificate management Experience implementing monitoring and observability systems About Our Team Our team spans CS degrees, philosophy, mathematics, and everything in between, or nothing formal at all. What everyone shares is a high bar for engineering quality. We work in-person because it's how we build trust and tackle hard problems together. Location: This position is in office in Vienna, VA. #J-18808-Ljbffr