Principal Systems Engineer

About Blacksmith - 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 month, running CI for 3,000+ companies and hit ~$10M in ARR in less than 2 years. We’ve more than tripled revenue since the start of 2026. - We operate thousands of bare-metal machines across multiple regions, regularly schedule 100k+ vCPUs concurrently, and run a petabyte-scale Ceph cluster that we manage ourselves. - We’ve raised $13.5M across Seed and Series A, led by Google Ventures (GV), 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. The Principal Systems Engineer at Blacksmith We are looking for a Principal Engineer to set the technical direction for our core infrastructure, critical to the Blacksmith product. This role operates at the organization level, owning architecture, solving complex systems problems, and driving initiatives that shape how Blacksmith grows, performs, and remains reliable. You will be one of the key technical authorities and a force multiplier at Blacksmith. You’ll raise engineering standards across the team, mentor senior talent and own production outcomes. This is a high impact, hands-on technical leader role. What you’ll be doing - Own and drive the architectural direction for critical infrastructure platforms. - Translate business and product strategy into long-term technical roadmaps and execution plans. - Accountable for production outcomes, including reliability, performance, and operational excellence. - Mentor senior engineers and act as a force multiplier. - Operate effectively in ambiguous problem spaces where both the problem and the solution need to be defined. You’re a good fit if you have - Deep familiarity with virtualization technologies such as Firecracker, QEMU, or Cloud Hypervisor, and an understanding of the tradeoffs between them. - Experience with distributed storage systems (e.g., Ceph) and a strong grasp of low-level file system performance, I/O tuning, and storage reliability at scale. - Comfort working at the kernel and filesystems level: experience with eBPF, cgroups, namespaces, or similar Linux primitives. - Track record of leading through influence and shaping technical direction while operating as an individual contributor. - Strong communication skills, with the ability to explain complex systems-level concepts to engineers, leadership, and non-technical stakeholders. Compensation and benefits - Medical, Vision, and Dental insurance. - Competitive base + equity. - 401K match. - Unlimited PTO. - Annual offsite. - Early-exercise stock options - 12 weeks fully paid parental leave (US)