Sandbox Runtime (srt) is Anthropic's lightweight OS-level sandbox, developed for Claude Code, that restricts the filesystem and network access of agents, local MCP servers, bash commands and arbitrary processes without a container.
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It is a research preview usable as a CLI or a library.
- 01
Wrap any command with srt to enforce filesystem, network and Unix-socket restrictions
- 02
Deny-by-default network allowlists enforced through built-in HTTP and SOCKS5 proxies
- 03
Read and write path rules configured in ~/.srt-settings.json
- 04
Native primitives: sandbox-exec on macOS, bubblewrap on Linux, a dedicated user plus Windows Filtering Platform rules on Windows
- 05
Drop-in sandboxing for MCP servers in .mcp.json and real-time violation monitoring on macOS
Open Source
Free and open source under the Apache-2.0 license, distributed on npm as @anthropic-ai/sandbox-runtime.
Best for
Developers and platform teams who want to run coding agents, MCP servers or untrusted scripts with tight filesystem and network limits on their own machines.
Not ideal for
Teams needing hardened multi-tenant isolation or production guarantees, since it is a beta research preview rather than a VM or container sandbox.
A simple, container-free way to put guardrails around agents and MCP servers, backed by the same approach Anthropic uses in Claude Code.
Actively released, with v0.0.81 published on October 20, 2026, and trending on GitHub in late October 2026.
As of
Is Sandbox Runtime (srt) free?+
Yes - Sandbox Runtime (srt) is Open Source. Free and open source under the Apache-2.0 license, distributed on npm as @anthropic-ai/sandbox-runtime.
Is Sandbox Runtime (srt) open source?+
Yes - Sandbox Runtime (srt) is open source. Free and open source under the Apache-2.0 license, distributed on npm as @anthropic-ai/sandbox-runtime.
Who is Sandbox Runtime (srt) best for?+
Developers and platform teams who want to run coding agents, MCP servers or untrusted scripts with tight filesystem and network limits on their own machines.
Who is Sandbox Runtime (srt) not ideal for?+
Teams needing hardened multi-tenant isolation or production guarantees, since it is a beta research preview rather than a VM or container sandbox.
What are the best Sandbox Runtime (srt) alternatives?+
The closest Sandbox Runtime (srt) alternatives on ai.dosa.dev are Pieces for Developers, agenttrace, Vibe Kanban - all listed under Developer Productivity & Workflow.
Who makes Sandbox Runtime (srt)?+
Sandbox Runtime (srt) is developed by Anthropic. It is listed in the Developer Productivity & Workflow category on ai.dosa.dev.
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