Runtime

The SDKs, CLI, MCP server and agent integrations for Runtime: sandboxes for AI agents. Each sandbox is a Firecracker microVM with its own Linux kernel, started from one call.

npm install withruntime   # TypeScript SDK, the `runtime` CLI and the MCP server
pip install withruntime   # Python SDK, sync and async

import { Sandbox } from "withruntime";

await using sbx = await Sandbox.create();
const result = await sbx.exec("python3 -c 'print(6 * 7)'");
console.log(result.exitCode, result.stdout);

from withruntime import Sandbox

with Sandbox.create() as sbx:
    result = sbx.exec("python3 -c 'print(6 * 7)'")
    print(result.exit_code, result.stdout)

The client reads RUNTIME_API_KEY, or the connection npx withruntime login saved on this machine. A new account starts on a free trial with no card. The quickstart takes it from there.

MCP server

The MCP server gives an agent every Runtime product as tools. It needs Node 22.12 or later and no API key. Claude Code:

claude mcp add --scope user runtime -- npx -y withruntime mcp

Cursor, Cline, Windsurf and other clients that take this shape:

{
  "mcpServers": {
    "runtime": { "command": "npx", "args": ["-y", "withruntime", "mcp"] }
  }
}

The first time, the server offers one tool, runtime_connect. The agent calls it and shows a link and a code; approve Connect agent in the browser, and every Runtime tool appears. A machine already connected with npx withruntime login skips this step. In CI, set RUNTIME_API_KEY instead.

Clients that connect over HTTP use https://api.withruntime.com/mcp (MCP Streamable HTTP) and sign in through the browser. The server is in the official MCP Registry as com.withruntime/runtime. Details: withruntime.com/docs/mcp.

Related MCP server: agent-sandbox-mcp

What is here

Documentation

• Start

• TypeScript and Python

• CLI and MCP

• Frameworks, and moving from E2B or Daytona

• Pricing

How Runtime compares

Pages that answer what people ask when choosing a sandbox, each with the providers' published rates and the date they were read:

• Best sandbox for AI agents

• Alternatives to E2B, Daytona, Modal and Vercel Sandbox

• E2B vs Daytona, and every comparison

• The agent sandbox price index: every provider's rates, also as CSV and JSON

• Sandbox cost calculator and Runtime's pricing

Tests

bun test in packages/cloud-sdk and python3 -m unittest discover -s tests in sdks/python run here as they are. The suites that start Runtime's API server in-process, including all of the Go, Java and Ruby tests, run in Runtime's main repository before each release.

Contributing

Each release copies the SDKs here from Runtime's main repository, so each commit here is one copy, named after the versions in its source; a copy made before those versions reach npm and PyPI says so. Issues are welcome. A pull request is reviewed here and carried into the next release with its author credited.

License

Apache-2.0. See LICENSE.