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Build secure, isolated code execution environments on Cloudflare. The Cloudflare Sandbox SDK lets you run untrusted code safely in isolated containers. Execute commands, manage files, run background processes, and expose services — all from your Workers applications. Perfect for AI code execution, interactive development environments, data analysis platforms, CI/CD systems, and any application that needs secure code execution at the edge.

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Key features

Secure isolation

Each sandbox runs in its own container with complete isolation from other workloads

Edge-native

Runs on Cloudflare’s global network for low-latency code execution worldwide

Code interpreter

Execute Python and JavaScript with rich outputs including matplotlib charts

File system access

Read, write, and manage files with full POSIX filesystem support

Command execution

Run any command with streaming support for real-time output

Preview URLs

Expose services running in your sandbox with public URLs

Git integration

Clone repositories directly into your sandbox environment

Background processes

Run long-running processes and manage their lifecycle

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Use cases

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AI code execution

Give AI models the ability to write and execute code safely. Perfect for:
  • AI agents that need to run Python for data analysis
  • Code generation tools that validate outputs
  • Interactive coding assistants

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Development environments

Build cloud-based IDEs and development tools:
  • Browser-based code editors
  • Interactive tutorials and learning platforms
  • Code playgrounds and REPLs

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Data analysis platforms

Run user-submitted data processing code:
  • Jupyter-style notebook environments
  • Custom data transformation pipelines
  • Statistical analysis tools

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CI/CD systems

Execute build and test workflows:
  • Automated testing environments
  • Build systems for user projects
  • Deployment automation

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How it works

The Sandbox SDK is built on Cloudflare’s container platform and uses Durable Objects to manage sandbox lifecycle:
1

Create a sandbox

Your Worker gets a reference to a sandbox using getSandbox(). Each sandbox is backed by a Durable Object that manages the container lifecycle.
2

Execute code

Call methods like exec(), writeFile(), or runCode() to interact with the sandbox. The SDK communicates with the container runtime over HTTP.
3

Get results

Receive execution results, file contents, or streamed output back in your Worker.
4

Automatic lifecycle

Containers hibernate when idle and wake up on demand. State persists across requests.

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Architecture

Worker → Sandbox Durable Object → Container Runtime → Shell/Filesystem
  • Worker: Your application code that calls the SDK
  • Sandbox Durable Object: Manages container lifecycle and routes requests
  • Container Runtime: Bun-based HTTP server running inside Docker containers
  • Shell/Filesystem: Ubuntu 22.04 with Python 3.11, Node.js 20, Git, and common utilities

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What’s included

Each sandbox container comes pre-installed with:
  • Python 3.11 with matplotlib, numpy, pandas, and ipython
  • Node.js 20 LTS with npm
  • Bun 1.x runtime
  • Git for repository operations
  • Common utilities: curl, wget, jq, and more
You can also use custom Docker images to add your own tools and dependencies.

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Quick example

import { getSandbox, type Sandbox } from '@cloudflare/sandbox';

export { Sandbox } from '@cloudflare/sandbox';

type Env = {
  Sandbox: DurableObjectNamespace<Sandbox>;
};

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const sandbox = getSandbox(env.Sandbox, 'my-sandbox');
    
    // Execute Python code
    const result = await sandbox.exec('python3 -c "print(2 + 2)"');
    
    return Response.json({ 
      output: result.stdout,
      success: result.success 
    });
  }
};

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Next steps

Installation

Install the SDK and set up your first project

Quickstart

Build your first sandbox application in 5 minutes

API reference

Explore the complete SDK API

Examples

See real-world applications and use cases

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Status

The Sandbox SDK is in open beta. The API is stable and safe for production use, but may evolve based on feedback before v1.0.

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