Claude code execution tool alternative: run Claude's code in your own sandbox

Anthropic's code execution tool runs Claude's code in a 1-CPU, 5 GiB container with no internet; your own sandbox adds packages and network.

Runtime bills a one-minute run as one minute: 1,000 of them cost $1.04 on Runtime against $4.17 under the tool's 5-minute minimum, once its free hours are used. A Runtime sandbox also reaches the internet you allow, installs any package, and runs code from any model. Anthropic's terms checked 25 September 2026; Runtime's are in pricing.

What the code execution tool is

A server tool in Anthropic's Messages API. It "allows Claude to run Bash commands and manipulate files, including writing code, in a secure, sandboxed environment." It is generally available and needs no beta header.

The container, as Anthropic documents it:

Anthropic lists the tool as not eligible for zero data retention.

What it costs

Anthropic's pricing, checked 25 September 2026:

• Free when the request also includes web search or web fetch (web_search_20260209, web_fetch_20260209 or later).
• Otherwise billed by execution time, with a 5-minute minimum.
• Each organization gets 1,550 free hours a month, then $0.05 per hour per container.
• Execution time is billed when files are in the request, even if the tool is not called.

The same work on Runtime at 1 vCPU and 5 GiB, which costs $0.03875 an hour waiting (memory plus the 50-millicore CPU floor) and $0.0625 with the CPU busy:

Tokens are left out of both columns. The tool's 1,550 free hours each month are worth $77.50 at its rate. For long, CPU-bound hours inside that allowance the tool is the cheaper choice; for short runs, and for code that needs the network, Runtime is.

Where your own sandbox does more

• Internet on your terms. Allow only the hosts a task needs, deny others, or switch it off, at create or at any time; the rules bind root inside the sandbox (the network).
• Any package, any image. pip install, npm install and sudo apt-get work, and a custom image built from a recipe, an image or a Dockerfile starts every sandbox ready (custom images).
• More than one CPU. A default sandbox has 2 vCPUs and 4 GiB, and vcpu, memory and disk are set per sandbox, rather than one fixed size.
• Whole-machine pause. A paused sandbox keeps files, memory and running processes for 1 to 365 days, and forks copy a running one.
• Any model. The same sandbox serves Claude, another provider's model, or your own code, and the Claude Agent SDK connects to it with runtimeMcpServer(sbx) (Claude Agent SDK).
• Keys it cannot read. A secret reaches the sandbox as a placeholder the host's proxy swaps for the value on its own hosts (secrets).

The Runtime equivalent

Define your own tool, say run_python(code), and run what Claude sends in a fresh sandbox that may reach PyPI and nothing else:

TypeScriptimport { Sandbox } from "withruntime";export async function runPython(code: string) {  await using sbx = await Sandbox.create({    network: { internet: true, allow: ["pypi.org", "*.pythonhosted.org"] },    timeoutSeconds: 600,    onLeaseEnd: "stop",  });  await sbx.files.write("/workspace/main.py", code);  const run = await sbx.exec(["python3", "main.py"], { timeoutMs: 120_000 });  return { exitCode: run.exitCode, stdout: run.stdout, stderr: run.stderr };}

Pythonfrom withruntime import Sandboxdef run_python(code: str) -> dict:    with Sandbox.create(        network={"internet": True, "allow": ["pypi.org", "*.pythonhosted.org"]},        timeout_seconds=600,        on_lease_end="stop",    ) as sbx:        sbx.files.write("/workspace/main.py", code)        run = sbx.exec(["python3", "main.py"], timeout_ms=120_000)        return {"exit_code": run.exit_code, "stdout": run.stdout, "stderr": run.stderr}

Return the dictionary as the tool result. The sandbox stops when the block ends, even after an error. With no size given it has 2 vCPUs and 4 GiB.

Which one fits

• Keep the code execution tool for analysis Claude does inside a conversation with the pre-installed libraries, especially alongside web search or web fetch, where it is free.
• Use your own sandbox when the code needs a package, an API or a repository from the internet, more than one CPU, a session that keeps its processes, or a model other than Claude.

Try it on the free trial, 50 sandbox hours with no card:

Terminalnpx withruntime sandbox run --trial -- python3 -c 'print(6 * 7)'

More: Runtime for Claude Code, OpenAI Code Interpreter alternative, run untrusted LLM code, egress control.

Sources

Checked 25 September 2026.

• Anthropic: code execution tool, including its containers, reuse and pricing sections
• Runtime pricing, the sandbox environment and frameworks

Facts on this page were checked on 25 September 2026.