Speed up your GitHub actions with Blacksmith. Run CI/CD 2x faster, download caches 4x faster, build Docker images 40x faster, and eliminate queue times. Start free today. Backed by Peak XV, Y Combinator and GV.
About the role
We are looking for a Systems Security Engineer to build and operate security controls at Blacksmith. Your primary focus will be our bare-metal fleet, with responsibility extending to our AWS control plane, application services and the broader organization. Found on 1752vc Careers, the job board for startup and VC roles.
What they're looking for
- Strong Linux systems experience, with the ability to debug production issues across the kernel, networking and storage stack
- A practical understanding of security fundamentals, including least privilege, defense in depth and threat modeling, and the ability to translate risks into technical solutions
- Experience with virtualization and Linux isolation primitives, such as Firecracker, KVM, namespaces and cgroups, and an understanding of their security boundaries and tradeoffs
- An understanding of storage access controls, tenant isolation and secure data deletion
- An understanding of how to use eBPF for runtime security monitoring, including observing process, file and network activity to detect suspicious behavior
- Experience securing production AWS environments, particularly IAM, networking and audit logging
More about this role
We started by building infrastructure to run CI workloads really fast. Our first product helps companies run GitHub Actions substantially faster and cheaper by owning and operating our own global fleet of bare-metal machines rather than renting generic cloud VMs.
Today, we orchestrate tens of millions of Firecracker VMs each week, running CI for 10,000+ companies and tens of millions in ARR. We’ve grown 20x so far in 2026.
We operate thousands of bare-metal machines across multiple regions, regularly schedule 300k+ vCPUs concurrently, and run a petabyte-scale Ceph cluster that we manage ourselves.
We’ve raised $125M from Seed to Series C, led by Sequoia, Google Ventures (GV) & Peak XV Partners, and we’re intentionally building a small, but exceptional team.
Blacksmith was founded by a team with deep systems and scaling experience, including building search/ads infrastructure at Faire, and operating large distributed systems at Cockroach Labs. Our GTM is led by Jon Boyer, formerly Head of Sales at Zapier.
We're now extending the same CI infrastructure into a broader platform: running agent sandboxes at scale and building our own background coding agent on top of it.
We are looking...
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