Anthropic Sandbox Runtime: developer tools for developers
Official site link, not an affiliate link. We do not have an approved referral link for Anthropic Sandbox Runtime.
Anthropic Sandbox Runtime helps you build software by this route: open-source sandbox that limits the files and network an AI agent or command can reach. It is best for developers who run AI agents, MCP servers or scripts and want OS-level file and network limits. People also use it to automate repetitive work. A free plan is available.
What it does
srt uses the operating system’s own sandboxing (sandbox-exec on macOS, bubblewrap on Linux, and an alpha Windows mode) plus proxy-based network filtering. By default network access is denied and writes are allowed only where you list them, so you open only the holes a task needs. Its README shows sandboxing a local MCP server by putting srt in front of the server command, and it can be used as a CLI or a library.
Official site:github.com/anthropics/sandbox-runtime.
Editorial note
Anthropic Sandbox Runtime (srt) is an open-source tool that wraps a command in OS-level file and network restrictions, without a container. Anthropic describes it as a research preview developed for Claude Code.
Who it’s for
- For: Developers who run AI agents, MCP servers or scripts and want OS-level file and network limits.
- Not ideal for: non-developers; it is a command-line and library tool.
Key use cases
- Build apps & code
- Automate work
What you can do with it
- Free access: Anthropic Sandbox Runtime is open source under the Apache-2.0 license, per its npm package. This matters when you want to test before you pay.
- Help documentation: Official pricing and product pages at github.com/anthropics/sandbox-runtime. This matters when you set it up yourself.
How to use Anthropic Sandbox Runtime: step-by-step tutorial
Five to eight steps from the account to a first useful result. Where the official guide names a control, the step uses that name. Where it does not, the step stays general.
- Open github.com and create an account on the free plan. You can reach a first result before you choose a paid plan.
- Install it: npm install -g @anthropic-ai/sandbox-runtime (Linux also needs bubblewrap, socat and ripgrep, per the README).
- Test it: srt "curl example.com" should be blocked unless the domain is allowed.
- Create ~/.srt-settings.json with the domains and folders the tool may use.
- In your .mcp.json, put "srt" as the command and the original server command in its arguments.
- Run your agent and check any blocked actions, then allow only what is truly needed.
These steps follow the official guide: sandbox-runtime on GitHub.
Frequently asked questions
Is Anthropic Sandbox Runtime free?
Yes. The npm package lists the Apache-2.0 license, checked October 24, 2026.
Does srt need Docker?
No. Its README says it enforces restrictions at the OS level without requiring a container.
Which systems does it support?
macOS and Linux, with Windows support in alpha, per the README.
Is it production-ready?
Anthropic labels it a beta research preview whose APIs and configuration may change.
Pricing
Prices checked on the official pricing page.
- Open source
-
Free
Apache-2.0; install with npm install -g @anthropic-ai/sandbox-runtime
- Limits: A research preview; configuration formats may change, and Linux needs extra packages.
- Plans change: vendors update limits and prices; confirm on the official page before you buy.
Facts
- Access
- Ongoing free plan
- Paid plans from
- Free
- Checked
- Category
- Category: Development tools (31 in the library).
- On the record
- Anthropic Sandbox Runtime is open source under the Apache-2.0 license, per its npm package.