Mirrai Careers

Head of Capacity

Blacksmith

SF / NYC Full-time Posted 30+ days ago
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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 week, running CI for 7,000+ companies and tens of millions in ARR. We’ve grown 10x so far in 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 $58.5M from Seed to Series B, led by 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. About the Role Blacksmith's infrastructure footprint is growing rapidly. Every quarter, we make decisions around servers, storage, networking, datacenter capacity, power, and geographic expansion. As demand for software validation grows, ensuring that capacity is available when and where we need it becomes increasingly important. We're looking for someone to own this problem. You'll work directly with the founders and infrastructure team to forecast demand, plan capacity growth, manage supplier relationships, and ensure Blacksmith can scale ahead of customer demand. Your job is simple to describe but difficult to execute: Make sure Blacksmith never runs out of capacity. What You'll Do * Own capacity planning across compute, storage, networking, and datacenter infrastructure. * Build forecasting models for infrastructure demand and growth. * Partner with engineering to understand future workload requirements. * Develop deployment plans across regions and datacenter partners. * Manage relationships with hardware vendors, datacenter providers, and infrastructure suppliers. * Lead hardware procurement and infrastructure expansion efforts. * Evaluate new suppliers, hardware platforms, and deployment opportunities. * Track utilization and ensure infrastructure investments are deployed efficiently. * Build processes and systems that allow Blacksmith to scale from thousands of servers to many times that number. You Are a Good Fit If You * Have experience operating large-scale infrastructure, cloud, hosting, networking, or datacenter environments. * Have experience with capacity planning, forecasting, or infrastructure operations. * Can balance long-term planning with day-to-day operational realities. * Are highly analytical and comfortable making decisions under uncertainty. * Have strong vendor management and negotiation skills. * Can work effectively with both technical and business stakeholders. * Enjoy solving operational problems at scale. * Want to work closely with founders on company-critical infrastructure decisions. * Enjoy working in person 5 days a week in SF/NYC. Bonus * Experience at a hyperscaler, cloud provider, hosting company, CDN, or infrastructure startup. * Experience procuring servers, networking equipment, storage, or datacenter capacity. * Experience managing infrastructure supply chains. * Experience with power planning, datacenter operations, or colocation providers. * Experience scaling infrastructure through periods of hypergrowth. What Success Looks Like Within your first year: * Blacksmith has a clear, data-driven capacity planning process. * Infrastructure growth is forecasted quarters ahead of demand. * Hardware procurement and deployment timelines are predictable. * Vendor and datacenter relationships are strong and scalable. * Leadership has visibility into future capacity constraints before they become operational issues. * Blacksmith can confidently scale infrastructure without becoming constrained by supply, deployment timelines, or planning failures. 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)

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