# Cloudflare Sandboxes hits GA: give your agents a real computer!

Hey there, it's Shiichan! Today I get to tell you about giving AI agents their very own computer. So exciting!

## What was announced?

Straight from Cloudflare's Blog: [Cloudflare Sandboxes](https://github.com/cloudflare/sandbox-sdk) and Cloudflare Containers are now generally available (GA)! It was announced on April 13, 2026.

A Sandbox is an isolated compute environment made for AI agents. It comes with a shell, a filesystem, and background processes, all in one place. It starts on demand and resumes from its previous state, so you're handing your agent a real place to get its hands dirty.

## The story so far

When you want an agent to write and run code, standing up a real, safe place for it to work has been surprisingly hard. You're running untrusted code, so you need isolation and you need scale. And a lot of setups even charge you for idle time while the agent waits on the LLM.

Sandboxes takes all of that off your plate. It runs on top of [Cloudflare Containers](https://blog.cloudflare.com/containers-are-available-in-public-beta-for-simple-global-and-programmable/), and Figma actually uses Containers for [Figma Make](https://www.figma.com/make/) as the foundation for running untrusted agent- and user-authored code at scale.

## What changes

You can hand your agent almost the same toolbox a human developer uses.

- Real PTY (pseudo-terminal) sessions you can drive over WebSocket
- Stateful code interpreters for Python, JavaScript, and TypeScript
- Spin up a dev server and check it right away through a public preview URL
- Watch file changes so you can build a save-and-react development loop

Pricing changed too: you're no longer billed during idle time (like while the agent waits for the LLM to reply), and you only pay for the CPU you actually use. It sounds small, but it's a really nice win!

## Dive Deep

The API is lovely and simple. From a Worker you grab a Sandbox, check out a Git repo, and run a command.

```
const sandbox = getSandbox(env.Sandbox, "agent-session-47");
await sandbox.gitCheckout("https://github.com/org/repo", {
  targetDir: "/workspace",
  depth: 1,
});
return sandbox.exec("npm", ["test"], { stream: true });
```

Here's the stateful code interpreter. Variables and imports persist across calls, so it works a lot like a Jupyter notebook.

```
const ctx = await sandbox.createCodeContext({ language: "python" });
await sandbox.runCode(pythonCode, { context: ctx });
```

When you want to expose a dev server, you can wait on a real readiness signal from the logs or the port before publishing, instead of guessing with a timer.

```
const server = await sandbox.startProcess("npm run dev", { cwd: "/workspace" });
await server.waitForLog(/Local:.*localhost:(\d+)/);
const { url } = await sandbox.exposePort(3000);
```

You reach the exposed server through a [preview URL](https://developers.cloudflare.com/sandbox/concepts/preview-urls/). There's also inotify-based filesystem watching streamed over Server-Sent Events, so you can drive event-driven loops like recompile-on-save.

The auth design is clever too. Instead of exposing credentials directly to the agent, a programmable egress proxy injects authentication at the network layer (there's a whole write-up in [Sandbox auth](https://blog.cloudflare.com/sandbox-auth)).

Snapshots are handy as well. You can preserve a whole environment, dependencies and modified files and all, stored in [R2](https://developers.cloudflare.com/r2/) with tiered caching for fast restores anywhere in the world. The [backup and restore guide](https://developers.cloudflare.com/sandbox/guides/backup-restore/) walks you through it.

Capacity went up too: on standard pricing you get up to 15,000 concurrent lite instances, 6,000 basic, and 1,000+ of the larger ones. And since it [only charges for actively used CPU cycles](https://developers.cloudflare.com/changelog/post/2025-11-21-new-cpu-pricing/) now, the wasteful idle billing is gone.

For the full method list, check the [Sandbox API reference](https://developers.cloudflare.com/sandbox/api/). To install, run `npm i @cloudflare/sandbox@latest`; the version at announcement was 0.8.9.

## Wrap-up

- Cloudflare's Sandboxes and Containers are now GA (April 13, 2026)
- You can hand an agent a real dev environment: shell, PTY, stateful code interpreter, preview URLs, and file watching
- Snapshots let you save and restore whole environments, stored in R2 plus tiered caching
- Concurrency capacity jumped, and there's no idle billing, you only pay for CPU used
- This one's perfect for anyone who wants agents to run code, and for developers hunting for a foundation for AI apps!