Blacksmith builds and operates a purpose-built cloud for running continuous integration (CI) workloads — specifically GitHub Actions — dramatically faster and cheaper than GitHub's own hosted runners. Instead of renting generic cloud VMs from hyperscalers like AWS or GCP, Blacksmith owns and operates its own global fleet of bare-metal servers running gaming-grade CPUs with co-located NVMe caching and persistent Docker layer storage. The result: CI jobs that run roughly 2x faster at 60–75% lower cost, requiring just a one-line YAML change to migrate. On top of raw compute, Blacksmith layers a CI observability console — log search, test analytics, automated failure comments on GitHub PRs — that fills gaps GitHub itself doesn't address. Now expanding beyond CI: the company is building Sandboxes (Firecracker microVM environments for AI coding agents) and Codesmith (a background coding agent that fixes failed CI checks automatically). The primary buyers are engineering teams at fast-growing software companies drowning in CI bottlenecks as AI coding tools generate far more pull requests than before. Founded in 2024 out of YC W24 by engineers from Faire and Cockroach Labs.