Sandcastle is a TypeScript library and CLI from Matt Pocock's AI Hero for orchestrating AI coding agents in isolated sandboxes.
Follow Sandcastle to get an email when its listing changes, such as new pricing or features. One digest a day at most, and you can unsubscribe anytime.
A single `sandcastle.run()` call starts an agent on its own branch, sandboxes it with a chosen provider, and merges the commits back, making it easy to run parallel AFK agents and review pipelines.
- 01
`sandcastle.run()` API that sandboxes an agent, applies a branch strategy and merges commits back
- 02
Agent providers for Claude Code, Codex, Copilot, Cursor, OpenCode and Pi
- 03
Native Bubblewrap and Seatbelt sandboxes plus Docker, Podman, E2B, Modal, Daytona, Vercel and Sprites providers
- 04
`sandcastle init` templates for simple loops, parallel planners and review pipelines
- 05
Hooks, iterations, structured output, agent session resume and run logs
Open Source
Sandcastle is free and open-source under the MIT license, published on npm as `@ai-hero/sandcastle`. You pay separately for the coding agents and models you run and for any cloud sandbox provider (E2B, Modal, Daytona, Vercel or Fly.io Sprites) you choose.
Best for
TypeScript developers who want to script parallel, unattended coding-agent runs with real isolation and git-based merge-back in their own repos or CI.
Not ideal for
Developers looking for a GUI agent manager or a hosted agent service, since Sandcastle is a pre-1.0 library that requires writing orchestration code.
A well-designed, provider-agnostic building block for running many sandboxed coding agents in parallel, backed by an active maintainer and fast-growing adoption.
v0.13.0 (November 2, 2026) made native Bubblewrap and Seatbelt sandboxes the documented default and extended session resume to more agents; v0.14.0 the same day added an E2B isolated sandbox provider. The repository passed 8,800 GitHub stars, appeared on GitHub's weekly trending list, and the npm package reports about 234,000 downloads a week.
As of
Is Sandcastle free?+
Yes - Sandcastle is Open Source. Sandcastle is free and open-source under the MIT license, published on npm as `@ai-hero/sandcastle`. You pay separately for the coding agents and models you run and for any cloud sandbox provider (E2B, Modal, Daytona, Vercel or Fly.io Sprites) you choose.
Is Sandcastle open source?+
Yes - Sandcastle is open source. Sandcastle is free and open-source under the MIT license, published on npm as `@ai-hero/sandcastle`. You pay separately for the coding agents and models you run and for any cloud sandbox provider (E2B, Modal, Daytona, Vercel or Fly.io Sprites) you choose.
Who is Sandcastle best for?+
TypeScript developers who want to script parallel, unattended coding-agent runs with real isolation and git-based merge-back in their own repos or CI.
Who is Sandcastle not ideal for?+
Developers looking for a GUI agent manager or a hosted agent service, since Sandcastle is a pre-1.0 library that requires writing orchestration code.
What are the best Sandcastle alternatives?+
The closest Sandcastle alternatives on ai.dosa.dev are Jules by Google, OpenHands, SWE-agent - all listed under Autonomous & Async Agents.
Who makes Sandcastle?+
Sandcastle is developed by AI Hero (Matt Pocock). It is listed in the Autonomous & Async Agents category on ai.dosa.dev.
Favorite this tool to revisit it later, or Zap it to contribute to the public vote count.