Senior Product Engineer
This is one of 4 engineering roles Blacksmith has open, and one of 2 at senior level. It went up 17 months ago.
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.
What you could work on
Build and evolve Codesmith, our background coding agent — designing the workflows, UI, and infrastructure that let engineers delegate coding tasks to AI and ship faster
Create tools that help engineers and AI agents debug flaky CI jobs: surfacing patterns in test failures, correlating logs with infrastructure signals, and making root cause analysis fast and intuitive
Work closely with design to ship polished, high-performance product surfaces across our analytics and observability platform, where engineers go to understand their CI systems
Prototype and iterate rapidly on AI-powered features — from natural language interfaces to automated fix generation — and own the full stack from prompt design to backend service to UI
Contribute to the architecture of the agent platform: how we run sandboxed workspaces, and orchestrate agent sessions
You are a good fit if you
Have strong CS fundamentals and a deep understanding of React and modern frontend development.
Can work closely with design to build polished, high-performance UIs — and aren’t afraid to go deep on browser performance, rendering bottlenecks, or complex component architecture.
Have 5+ years of software development experience.
Enjoy working in person 5 days a week in NYC.
Enjoy working at a very early-stage startup and are comfortable with ambiguity.
Bonus
You’ve dabbled in your own side hustles or start-up projects.
You’re comfortable creating new processes and iterating on them quickly.
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)
Check your resume against this role
Drop your resume. You get a 0-100 fit score against the actual job description, plus the reasoning and the gaps worth closing first. Private to you.
Score this once, or every future role
Start the candidate journey and every new role on the board gets scored against you.
Five minutes. Tell us what you’re after, drop your resume once, pick how we should reach out. You get a candid read back and you only hear from us when a role fits.