Blacksmith Sandboxes
Last verified 2026-08-10
Blacksmith Sandboxes come from Blacksmith, a CI-runner company, and reuse that CI infrastructure for agents. Each sandbox is a full VM (not a lightweight code interpreter) that is identical to CI down to the root filesystem, caching and toolchains, so an agent can run Docker, integration tests and multi-architecture builds (x86, ARM; Linux, Windows, Mac). Sandboxes boot from managed environment snapshots that capture a project's dependencies, and are created from a TypeScript SDK (@useblacksmith/sandbox). Blacksmith is explicit that this is not the tool for sub-second cold starts or zero-system-access code interpreters: it targets agents bottlenecked by build and test speed. As of this writing it is in beta (waitlist) with no published pricing.
Key specs
| Isolation | Full VM |
| Pricing model | Beta (waitlist), pricing not published |
| Persistence | Managed environment snapshots |
| Languages | any |
| Integrations | TypeScript SDK |
| Deployment | Managed cloud |
| Free tier | Beta access (waitlist) |
| Status | Beta (waitlist) |
| Isolation | Full VM |
| Architectures | x86, ARM |
| SDK | @useblacksmith/sandbox |
Strengths
- Full CI-grade VMs (Docker, system packages, services)
- Boots from managed environment snapshots
- High single-core CPU performance for builds and tests
- Multi-architecture (x86, ARM) and multi-OS
Trade-offs
- Beta / waitlist, no public pricing yet
- Not built for sub-second cold starts or lightweight code interpreters
- Newest, least-proven entrant
Best for: Coding agents bottlenecked by build/test speed that need full, CI-identical VMs with Docker.
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