If an agent is acting like a developer, this means cloning repositories, building code in many languages, running development servers, etc. To do these things effectively, they will often need a full computer (and if they don’t, they can reach for something lightweight!).

Many developers are stitching together solutions using VMs or existing container solutions, but there are lots of hard problems to solve:

• Burstiness - With each session needing its own sandbox, you often need to spin up many sandboxes quickly, but you don’t want to pay for idle compute on standby.

• Quick state restoration - Each session should start quickly and re-start quickly, resuming past state.

• Security - Agents need to access services securely, but can’t be trusted with credentials.

• Control - It needs to be simple to programmatically control sandbox lifecycle, execute commands, handle files, and more.

• Ergonomics - You need to give a simple interface for both humans and agents to do common operations.

We’ve spent time solving these issues so you don’t have to. Since our initial launch we’ve made Sandboxes an even better place to run agents at scale. We’ve worked with our initial partners such as Figma, who run agents in containers with Figma Make:

“Figma Make is built to help builders and makers of all backgrounds go from idea to production, faster. To deliver on that goal, we needed an infrastructure solution that could provide reliable, highly-scalable sandboxes where we could run untrusted agent- and user-authored code. Cloudflare Containers is that solution.”

- Alex Mullans, AI and Developer Platforms at Figma

We want to bring Sandboxes to even more great organizations, so today we are excited to announce that Sandboxes and Cloudflare Containers are both generally available.

Let’s take a look at some of the recent changes to Sandboxes:

• Secure credential injection lets you make authenticated calls without the agent ever having credential access  

• PTY support gives you and your agent a real terminal

• Persistent code interpreters give your agent a place to execute stateful Python, JavaScript, and TypeScript out of the box

• Background processes and live preview URLs provide a simple way to interact with development servers and verify in-flight changes

• Filesystem watching improves iteration speed as agents make changes

• Snapshots let you quickly recover an agent's coding session

• Higher limits and Active CPU Pricing let you deploy a fleet of agents at scale without paying for unused CPU cycles

Before getting into some of the recent changes, let’s quickly look at the basics.

A Cloudflare Sandbox is a persistent, isolated environment powered by Cloudflare Containers. You ask for a sandbox by name. If it's running, you get it. If it's not, it starts. When it's idle, it sleeps automatically and wakes when it receives a request. It’s easy to programmatically interact with the sandbox using methods like exec, gitClone, writeFile and more.

import { getSandbox } from "@cloudflare/sandbox";
export { Sandbox } from "@cloudflare/sandbox";

export default {
  async fetch(request: Request, env: Env) {
    // Ask for a sandbox by name. It starts on demand.
    const sandbox = getSandbox(env.Sandbox, "agent-session-47");

    // Clone a repository into it.
    await sandbox.gitCheckout("https://github.com/org/repo", {
      targetDir: "/workspace",
      depth: 1,
    });

    // Run the test suite. Stream output back in real time.
    return sandbox.exec("npm", ["test"], { stream: true });
  },
};

As long as you provide the same ID, subsequent requests can get to this same sandbox from anywhere in the world.

One of the hardest problems in agentic workloads is authentication. You often need agents to access private services, but you can't fully trust them with raw credentials. 

Sandboxes solve this by injecting credentials at the network layer using a programmable egress proxy. This means that sandbox agents never have access to credentials and you can fully customize auth logic as you see fit:

class OpenCodeInABox extends Sandbox {
  static outboundByHost = {
    "my-internal-vcs.dev": (request, env, ctx) => {
      const headersWithAuth = new Headers(request.headers);
      headersWithAuth.set("x-auth-token", env.SECRET);
      return fetch(request, { headers: headersWithAuth });
    }
  }
}

For a deep dive into how this works — including identity-aware credential injection, dynamically modifying rules, and integrating with Workers bindings — read our recent blog post on Sandbox auth.

Early agent systems often modeled shell access as a request-response loop: run a command, wait for output, stuff the transcript back into the prompt, repeat. It works, but it is not how developers actually use a terminal. 

Humans run something, watch output stream in, interrupt it, reconnect later, and keep going. Agents benefit from that same feedback loop.

In February, we shipped PTY support. A pseudo-terminal session in a Sandbox, proxied over WebSocket, compatible with xterm.js.

Just call sandbox.terminal to serve the backend:

// Worker: upgrade a WebSocket connection into a live terminal session
export default {
  async fetch(request: Request, env: Env) {
    const url = new URL(request.url);
    if (url.pathname === "/terminal") {
      const sandbox = getSandbox(env.Sandbox, "my-session");
      return sandbox.terminal(request, { cols: 80, rows: 24 });
    }
    return new Response("Not found", { status: 404 });
  },
};

And use xterm addon to call it from the client:

// Browser: connect xterm.js to the sandbox shell
import { Terminal } from "xterm";
import { SandboxAddon } from "@cloudflare/sandbox/xterm";

const term = new Terminal();
const addon = new SandboxAddon({
  getWebSocketUrl: ({ origin }) => `${origin}/terminal`,
});

term.loadAddon(addon);
term.open(document.getElementById("terminal-container")!);
addon.connect({ sandboxId: "my-session" });

This allows agents and developers to use a full PTY to debug those sessions live.

Each terminal session gets its own isolated shell, its own working directory, its own environment. Open as many as you need, just like you would on your own machine. Output is buffered server-side, so reconnecting replays what you missed.

For data analysis, scripting, and exploratory workflows, we also ship a higher-level abstraction: a persistent code execution context.

The key word is “persistent.” Many code interpreter implementations run each snippet in isolation, so state disappears between calls. You can't set a variable in one step and read it in the next.

Sandboxes allow you to create “contexts” that persist state. Variables and imports persist across calls the same way they would in a Jupyter notebook:

// Create a Python context. State persists for its lifetime.
const ctx = await sandbox.createCodeContext({ language: "python" });

// First execution: load data
await sandbox.runCode(`
  import pandas as pd
  df = pd.read_csv('/workspace/sales.csv')
  df['margin'] = (df['revenue'] - df['cost']) / df['revenue']
`, { context: ctx });

// Second execution: df is still there
const result = await sandbox.runCode(`
  df.groupby('region')['margin'].mean().sort_values(ascending=False)
`, { context: ctx, onStdout: (line) => console.log(line.text) });

// result contains matplotlib charts, structured json output, and Pandas tables in HTML

Agents are more useful when they can build something and show it to the user immediately. Sandboxes support background processes, readiness checks, and preview URLs. This lets an agent start a development server and share a live link without leaving the conversation.

// Start a dev server as a background process
const server = await sandbox.startProcess("npm run dev", {
  cwd: "/workspace",
});

// Wait until the server is actually ready — don't just sleep and hope
await server.waitForLog(/Local:.*localhost:(\d+)/);

// Expose the running service with a public URL
const { url } = await sandbox.exposePort(3000);

// url is a live public URL the agent can share with the user
console.log(`Preview: ${url}`);

With waitForPort() and waitForLog(), agents can sequence work based on real signals from the running program instead of guesswork. This is much nicer than a common alternative, which is usually some version of sleep(2000) followed by hope.

Modern development loops are event-driven. Save a file, rerun the build. Edit a config, restart the server. Change a test, rerun the suite.

We shipped sandbox.watch() in March. It returns an SSE stream backed by native inotify, the kernel mechanism Linux uses for filesystem events.

import { parseSSEStream, type FileWatchSSEEvent } from '@cloudflare/sandbox';

const stream = await sandbox.watch('/workspace/src', {
  recursive: true,
  include: ['*.ts', '*.tsx']
});

for await (const event of parseSSEStream<FileWatchSSEEvent>(stream)) {
  if (event.type === 'modify' && event.path.endsWith('.ts')) {
    await sandbox.exec('npx tsc --noEmit', { cwd: '/workspace' });
  }
}

This is one of those primitives that quietly changes what agents can do. An agent that can observe the filesystem in real time can participate in the same feedback loops as a human developer.

Imagine a (human) developer working on their laptop. They git clone a repo, run npm install, write code, push a PR, then close their laptop while waiting for code review. When it’s time to resume work, they just re-open the laptop and continue where they left off.

If an agent wants to replicate this workflow on a naive container platform, you run into a snag. How do you resume where you left off quickly? You could keep a sandbox running, but then you pay for idle compute. You could start fresh from the container image, but then you have to wait for a long git clone and npm install.

Our answer is snapshots, which will be rolling out in the coming weeks.

A snapshot preserves a container's full disk state, OS config, installed dependencies, modified files, data files and more. Then it lets you quickly restore it later.

You can configure a Sandbox to automatically snapshot when it goes to sleep.

class AgentDevEnvironment extends Sandbox {
  sleepAfter = "5m";
  persistAcrossSessions = {type: "disk"}; // you can also specify individual directories
}

You can also programmatically take a snapshot and manually restore it. This is useful for checkpointing work or forking sessions. For instance, if you wanted to run four instances of an agent in parallel, you could easily boot four sandboxes from the same state.

class AgentDevEnvironment extends Sandbox {}

async forkDevEnvironment(baseId, numberOfForks) {
  const baseInstance = await getSandbox(baseId);
  const snapshotId = await baseInstance.snapshot();

  const forks = Array.from({ length: numberOfForks }, async (_, i) => {
    const newInstance = await getSandbox(`${baseId}-fork-${i}`);
    return newInstance.start({ snapshot: snapshotId });
  });

  await Promise.all(forks);
}

Snapshots are stored in R2 within your account, giving you durability and location-independence. R2's tiered caching system allows for fast restores across all of Region: Earth.

In future releases, live memory state will also be captured, allowing running processes to resume exactly where they left off. A terminal and an editor will reopen in the exact state they were in when last closed.

If you are interested in restoring session state before snapshots go live, you can use the backup and restore methods today. These also persist and restore directories using R2, but are not as performant as true VM-level snapshots. Though they still can lead to considerable speed improvements over naively recreating session state.

^{Booting a sandbox, cloning  ‘axios’, and npm installing takes 30 seconds. Restoring from a backup takes two seconds.}

Stay tuned for the official snapshot release.

Since our initial launch, we’ve been steadily increasing capacity. Users on our standard pricing plan can now run 15,000 concurrent instances of the lite instance type, 6,000 instances of basic, and over 1,000 concurrent larger instances. Reach out to run even more!

We also changed our pricing model to be more cost effective running at scale. Sandboxes now only charge for actively used CPU cycles. This means that you aren’t paying for idle CPU while your agent is waiting for an LLM to respond.

Nine months ago, we shipped a sandbox that could run commands and access a filesystem. That was enough to prove the concept.

What we have now is different in kind. A Sandbox today is a full development environment: a terminal you can connect a browser to, a code interpreter with persistent state, background processes with live preview URLs, a filesystem that emits change events in real time, egress proxies for secure credential injection, and a snapshot mechanism that makes warm starts nearly instant. 

When you build on this, a satisfying pattern emerges: agents that do real engineering work. Clone a repo, install it, run the tests, read the failures, edit the code, run the tests again. The kind of tight feedback loop that makes a human engineer effective — now the agent gets it too.

We're at version 0.8.9 of the SDK. You can get started today:

npm i @cloudflare/sandbox@latest

The sandbox is an important step beyond simple containers, because it gives you a few things:

• Security: Any untrusted end user (or a rogue LLM) can run in the sandbox and not compromise the host machine or other sandboxes running alongside it. This is traditionally (but not always) accomplished with a microVM.

• Speed: An end user should be able to pick up a new sandbox quickly and restore the state from a previously used one quickly.

• Control: The trusted platform needs to be able to take actions within the untrusted domain of the sandbox. This might mean mounting files in the sandbox, or controlling which requests access it, or executing specific commands.

Today, we’re excited to add another key component of control to our Sandboxes and all Containers: outbound Workers. These are programmatic egress proxies that allow users running sandboxes to easily connect to different services, add observability, and, importantly for agents, add flexible and safe authentication.

Here’s a quick look at adding a secret key to a header using an outbound Worker:

class OpenCodeInABox extends Sandbox {
  static outboundByHost = {
    "github.com": (request, env, ctx) => {
      const headersWithAuth = new Headers(request.headers);
      headersWithAuth.set("x-auth-token", env.SECRET);
      return fetch(request, { headers: headersWithAuth });
    }
  }
}

Any time code running in the sandbox makes a request to “github.com”, the request is proxied through the handler. This allows you to do anything you want on each request, including logging, modifying, or cancelling it. In this case, we’re safely injecting a secret (more on this later). The proxy runs on the same machine as any sandbox, has access to distributed state, and can be easily modified with simple JavaScript.

We’re excited about all the possibilities this adds to Sandboxes, especially around authentication for agents. Before going into details, let’s back up and take a quick tour of traditional forms of auth, and why we think there’s something better.

The core issue with agentic auth is that we can’t fully trust the workload. While our LLMs aren’t nefarious (at least not yet), we still need to be able to apply protections to ensure they don’t use data inappropriately or take actions they shouldn’t.

A few common methods exist to provide auth to agents, and each has downsides:

Standard API tokens are the most basic method of authentication, typically injected into applications via environment variables or in mounted secrets files. This is the arguably simplest method, but least secure. You have to trust that the sandbox won’t somehow be compromised or accidentally exfiltrate the token while making a request. Since you can’t fully trust the agent, you’ll need to set up token expiry and rotation, which can be a hassle.

Workload identity tokens, such as OIDC tokens, can solve some of this pain. Rather than granting the agent a token with general permissions, you can grant it a token that attests its identity. Now, rather than the agent having direct access to some service with a token, it can exchange an identity token for a very short-lived access token. The OIDC token can be invalidated after a specific agent’s workflow completes, and expiry is easier to manage. One of the biggest downsides of workload identity tokens is the potential inflexibility of integrations. Many services don’t have first-class support for OIDC, so in order to get working integrations with upstream services, platforms will need to roll their own token-exchanging services. This makes adoption difficult.

Custom proxies provide maximum flexibility, and can be paired with workload identity tokens. If you can pass some or all of your sandbox egress through a trusted piece of code, you can insert whatever rules you need. Maybe the upstream service your agent is communicating with has a bad RBAC story, and it can’t provide granular permissions. No problem, just write the controls and permissions yourself! This is a great option for agents that you need to lock down with granular controls. However, how do you intercept all of a sandbox’s traffic? How do you set up a proxy that is dynamic and easily programmable? How do you proxy traffic efficiently? These aren’t easy problems to solve.

With those imperfect methods in mind, what does an ideal auth mechanism look like?

Ideally, it is:

• Zero trust. No token is ever granted to an untrusted user for any amount of time.

• Simple. Easy to author. Doesn’t involve a complex system of minting, rotating, and decrypting tokens.

• Flexible. We don’t rely on the upstream system to provide the granular access we need. We can apply whatever rules we want.

• Identity-aware. We can identify the sandbox making the call and apply specific rules for it.

• Observable. We can easily gather information about what calls are being made.

• Performant. We aren’t round-tripping to a centralized or slow source of truth.

• Transparent. The sandboxed workload doesn’t have to know about it. Things just work.

• Dynamic. We can change rules on the fly.

We believe outbound Workers for Sandboxes fit the bill on all of these. Let’s see how.

First, we’ll look at a very basic example: logging requests and denying specific actions.

In this case, we’ll use the outbound function, which intercepts all outgoing HTTP requests from the sandbox. With a few lines of JavaScript, it’s easy to ensure only GETs are made and log then deny any disallowed methods.

class MySandboxedApp extends Sandbox {
  static outbound = (req, env, ctx) => {
    // Deny any non-GET action and log
    if (req.method !== 'GET') {
      console.log(`Container making ${req.method} request to: ${req.url}`);
      return new Response('Not Allowed', { status: 405, statusText: 'Method Not Allowed'});
    }

    // Proceed if it is a GET request
    return fetch(req);
  };
}

This proxy runs on Workers and runs on the same machine as the sandboxed VM. Workers were built for quick response times, often sitting in front of cached CDN traffic, so additional latency is extremely minimal.

Because this is running on Workers, we get observability out of the box. You can view logs and outbound requests in the Workers dashboard or export them to your application performance monitoring tool of choice.

How would we use this to enforce a zero trust environment for our agent? Let’s imagine we want to make a request to a private GitHub instance, but we never want our LLM to access a private token.

We can use outboundByHost to define functions for specific domains or IPs. In this case, we’ll inject a protected credential if the domain is “my-internal-vcs.dev”. The sandboxed agent never has access to these credentials.

class OpenCodeInABox extends Sandbox {
  static outboundByHost = {
    "my-internal-vcs.dev": (request, env, ctx) => {
      const headersWithAuth = new Headers(request.headers);
      headersWithAuth.set("x-auth-token", env.SECRET);
      return fetch(request, { headers: headersWithAuth });
    }
  }
}

It is also easy to conditionalize the response based on the identity of the container. You don’t have to inject the same tokens for every sandbox instance.

 static outboundByHost = {
  "my-internal-vcs.dev": (request, env, ctx) => {
    // note: KV is encrypted at rest and in transit
    const authKey = await env.KEYS.get(ctx.containerId);

    const requestWithAuth = new Request(request);
    requestWithAuth.headers.set("x-auth-token", authKey);
    return fetch(requestWithAuth);
  }
}

As you may have noticed in the last example, another major advantage of using outbound Workers is that it makes integration into the Workers ecosystem easier. Previously, if a user wanted to access R2, they would have to inject an R2 credential, then make a call from their container to the public R2 API. Same for KV, Agents, other Containers, other Worker services, etc.

Now, you just call any binding from your outbound Workers.

class MySandboxedApp extends Sandbox {
  static outboundByHost = {
    "my.kv": async (req, env, ctx) => {
      const key = keyFromReq(req);
      const myResult = await env.KV.get(key);
      return new Response(myResult);
    },
    "objects.cf": async (req, env, ctx) => {
      const prefix = ctx.containerId
      const path = pathFromRequest(req);
      const object = await env.R2.get(`${prefix}/${path}`);
      const myResult = await env.KV.get(key);
      return new Response(myResult);
    },
  };
}

Rather than parsing tokens and setting up policies, we can easily conditionalize access with code and whatever logic we want. In the R2 example, we also were able to use the sandbox’s ID to further scope access with ease.

Networking control should also be dynamic. On many platforms, config for Container and VM networking is static, looking something like this:

{
  defaultEgress: "block",
  allowedDomains: ["github.com", "npmjs.org"]
}

This is better than nothing, but we can do better. For many sandboxes, we might want to apply a policy on start, but then override it with another once specific operations have been performed.

For instance, we can boot a sandbox, grab our dependencies via NPM and Github, and then lock down egress after that. This ensures that we open up the network for as little time as possible.

To achieve this, we can use outboundHandlers, which allows us to define arbitrary outbound handlers that can be applied programmatically using the setOutboundHandler method. Each of these also takes params, allowing you to customize behavior from code. In this case, we will allow some hostnames with the custom “allowHosts” policy, then turn off HTTP.

class MySandboxedApp extends Sandbox {
  static outboundHandlers = {
    async allowHosts(req, env, { params }) {
     const url = new URL(request.url);
     const allowedHostname = params.allowedHostnames.includes(url.hostname);

      if (allowedHostname) {
        return await fetch(newRequest);
      } else {
        return new Response(null, { status: 403, statusText: "Forbidden" });
      }
    }
    
    async noHttp(req) {
      return new Response(null, { status: 403, statusText: "Forbidden" });
    }
  }
}

async setUpSandboxes(req, env) {
  const sandbox = await env.SANDBOX.getByName(userId);
  await sandbox.setOutboundHandler("allowHosts", {
    allowedHostnames: ["github.com", "npmjs.org"]
  });
  await sandbox.gitClone(userRepoURL)
  await sandbox.exec("npm install")
  await sandbox.setOutboundHandler("noHttp");
}

This could be extended even further. Your agent might ask the end user a question like “Do you want to allow POST requests to cloudflare.com?” based on whatever tools it needs at that time. With dynamic outbound Workers, you can easily modify the sandbox rules on the fly to provide this level of control.

To do anything useful with requests beyond allowing or denying them, you need to have access to the content. This means that if you’re making HTTPS requests, they need to be decrypted by the Workers proxy.

To achieve this, a unique ephemeral certificate authority (CA) and private key are created for each Sandbox instance, and the CA is placed into the sandbox. By default, sandbox instances will trust this CA, while standard container instances can opt into trusting it, for instance by calling sudo update-ca-certificates.

export class MyContainer extends Container {
  interceptHttps = true;
}

MyContainer.outbound = (req, env, ctx) => {
  // All HTTP(S) requests will trigger this hook.
  return fetch(req);
};

TLS traffic is proxied by a Cloudflare isolated network process by performing a TLS handshake. It creates a leaf CA from an ephemeral and unique private key and uses the SNI extracted in the ClientHello. It will then invoke in the same machine the  configured Worker to handle the HTTPS request.

Our ephemeral private key and CA will never leave our container runtime sidecar process, and is never shared across other container sidecar processes.

With this in place, outbound Workers act as a truly transparent proxy. The sandbox doesn't need any awareness of specific protocols or domains — all HTTP and HTTPS traffic flows through the outbound handler for filtering or modification.

To enable the functionality shown above in both Container and Sandbox, we added new methods to the ctx.container object: interceptOutboundHttp and interceptOutboundHttps, which intercept outgoing requests on specific hostnames (with basic glob matching), IP ranges, and it can be used to intercept all outbound requests. These methods are called with a WorkerEntrypoint, which gets set up as the front door to the outbound Worker.

export class MyWorker extends WorkerEntrypoint {
 fetch() {
   return new Response(this.ctx.props.message);
 }
}

// ... inside your container DurableObject ...
this.ctx.container.start({ enableInternet: false });
const outboundWorker = this.ctx.exports.MyWorker({ props: { message: 'hello' } });
await this.ctx.container.interceptOutboundHttp('15.0.0.1:80', outboundWorker);

// From now on, all HTTP requests to 15.0.0.1:80 return "hello"
await this.waitForContainerToBeHealthy();

// You can decide to return another message now...
const secondOutboundWorker = this.ctx.exports.MyWorker({ props: { message: 'switcheroo' } });
await this.ctx.container.interceptOutboundHttp('15.0.0.1:80', secondOutboundWorker);
// all HTTP requests to 15.0.0.1 now show "switcheroo", even on connections that were
// open before this interceptOutboundHttp

// You can even set hostnames, CIDRs, for both IPv4 and IPv6
await this.ctx.container.interceptOutboundHttp('example.com', secondOutboundWorker);
await this.ctx.container.interceptOutboundHttp('*.example.com', secondOutboundWorker);
await this.ctx.container.interceptOutboundHttp('123.123.123.123/23', secoundOutboundWorker);

All proxying to Workers happens locally on the same machine that runs the sandbox VM. Even though communication between container and Worker is “authless”, it is secure.

These methods can be called at any time, before or after starting the container, even while connections are still open. Connections that send multiple HTTP requests will automatically pick up a new entrypoint, so updating outbound Workers will not break existing TCP connections or interrupt HTTP requests.

Local development with wrangler dev also has support for egress interception. To make it possible, we automatically spawn a sidecar process inside the local container’s network namespace. We called this sidecar component proxy-everything. Once proxy-everything is attached, it applies the appropriate TPROXY nftable rules, routing matching traffic from the local Container to workerd, Cloudflare’s open source JavaScript runtime, which runs the outbound Worker. This allows the local development experience to mirror what happens in prod, so testing and development remain simple.

If you haven’t tried Cloudflare Sandboxes, check out the Getting Started guide. If you are a current user of Containers or Sandboxes, start using outbound Workers now by reading the documentation and upgrading to @cloudflare/containers@0.3.0 or @cloudflare/sandbox@0.8.9.

Editorial note: As of January 30, 2026, Moltbot has been renamed to OpenClaw.

The Internet woke up this week to a flood of people buying Mac minis to run Moltbot (formerly Clawdbot), an open-source, self-hosted AI agent designed to act as a personal assistant. Moltbot runs in the background on a user's own hardware, has a sizable and growing list of integrations for chat applications, AI models, and other popular tools, and can be controlled remotely. Moltbot can help you with your finances, social media, organize your day — all through your favorite messaging app.

But what if you don’t want to buy new dedicated hardware? And what if you could still run your Moltbot efficiently and securely online? Meet Moltworker, a middleware Worker and adapted scripts that allows running Moltbot on Cloudflare's Sandbox SDK and our Developer Platform APIs.

Cloudflare Workers has never been as compatible with Node.js as it is now. Where in the past we had to mock APIs to get some packages running, now those APIs are supported natively by the Workers Runtime.

This has changed how we can build tools on Cloudflare Workers. When we first implemented Playwright, a popular framework for web testing and automation that runs on Browser Rendering, we had to rely on memfs. This was bad because not only is memfs a hack and an external dependency, but it also forced us to drift away from the official Playwright codebase. Thankfully, with more Node.js compatibility, we were able to start using node:fs natively, reducing complexity and maintainability, which makes upgrades to the latest versions of Playwright easy to do.

The list of Node.js APIs we support natively keeps growing. The blog post “A year of improving Node.js compatibility in Cloudflare Workers” provides an overview of where we are and what we’re doing.

We measure this progress, too. We recently ran an experiment where we took the 1,000 most popular NPM packages, installed and let AI loose, to try to run them in Cloudflare Workers, Ralph Wiggum as a "software engineer" style, and the results were surprisingly good. Excluding the packages that are build tools, CLI tools or browser-only and don’t apply, only 15 packages genuinely didn’t work. That's 1.5%.

Here’s a graphic of our Node.js API support over time:

We put together a page with the results of our internal experiment on npm packages support here, so you can check for yourself.

Moltbot doesn’t necessarily require a lot of Workers Node.js compatibility because most of the code runs in a container anyway, but we thought it would be important to highlight how far we got supporting so many packages using native APIs. This is because when starting a new AI agent application from scratch, we can actually run a lot of the logic in Workers, closer to the user.

The other important part of the story is that the list of products and APIs on our Developer Platform has grown to the point where anyone can build and run any kind of application — even the most complex and demanding ones — on Cloudflare. And once launched, every application running on our Developer Platform immediately benefits from our secure and scalable global network.

Those products and services gave us the ingredients we needed to get started. First, we now have Sandboxes, where you can run untrusted code securely in isolated environments, providing a place to run the service. Next, we now have Browser Rendering, where you can programmatically control and interact with headless browser instances. And finally, R2, where you can store objects persistently. With those building blocks available, we could begin work on adapting Moltbot.

Moltbot on Workers, or Moltworker, is a combination of an entrypoint Worker that acts as an API router and a proxy between our APIs and the isolated environment, both protected by Cloudflare Access. It also provides an administration UI and connects to the Sandbox container where the standard Moltbot Gateway runtime and its integrations are running, using R2 for persistent storage.

^{High-level architecture diagram of Moltworker.}

Let's dive in more.

Cloudflare AI Gateway acts as a proxy between your AI applications and any popular AI provider, and gives our customers centralized visibility and control over the requests going through.

Recently we announced support for Bring Your Own Key (BYOK), where instead of passing your provider secrets in plain text with every request, we centrally manage the secrets for you and can use them with your gateway configuration.

An even better option where you don’t have to manage AI providers' secrets at all end-to-end is to use Unified Billing. In this case you top up your account with credits and use AI Gateway with any of the supported providers directly, Cloudflare gets charged, and we will deduct credits from your account.

To make Moltbot use AI Gateway, first we create a new gateway instance, then we enable the Anthropic provider for it, then we either add our Claude key or purchase credits to use Unified Billing, and then all we need to do is set the ANTHROPIC_BASE_URL environment variable so Moltbot uses the AI Gateway endpoint. That’s it, no code changes necessary.

Once Moltbot starts using AI Gateway, you’ll have full visibility on costs and have access to logs and analytics that will help you understand how your AI agent is using the AI providers.

Note that Anthropic is one option; Moltbot supports other AI providers and so does AI Gateway. The advantage of using AI Gateway is that if a better model comes along from any provider, you don’t have to swap keys in your AI Agent configuration and redeploy — you can simply switch the model in your gateway configuration. And more, you specify model or provider fallbacks to handle request failures and ensure reliability.

Last year we anticipated the growing need for AI agents to run untrusted code securely in isolated environments, and we announced the Sandbox SDK. This SDK is built on top of Cloudflare Containers, but it provides a simple API for executing commands, managing files, running background processes, and exposing services — all from your Workers applications.

In short, instead of having to deal with the lower-level Container APIs, the Sandbox SDK gives you developer-friendly APIs for secure code execution and handles the complexity of container lifecycle, networking, file systems, and process management — letting you focus on building your application logic with just a few lines of TypeScript. Here’s an example:

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

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const sandbox = getSandbox(env.Sandbox, 'user-123');

    // Create a project structure
    await sandbox.mkdir('/workspace/project/src', { recursive: true });

    // Check node version
    const version = await sandbox.exec('node -v');

    // Run some python code
    const ctx = await sandbox.createCodeContext({ language: 'python' });
    await sandbox.runCode('import math; radius = 5', { context: ctx });
    const result = await sandbox.runCode('math.pi * radius ** 2', { context: ctx });

    return Response.json({ version, result });
  }
};

This fits like a glove for Moltbot. Instead of running Docker in your local Mac mini, we run Docker on Containers, use the Sandbox SDK to issue commands into the isolated environment and use callbacks to our entrypoint Worker, effectively establishing a two-way communication channel between the two systems.

The good thing about running things in your local computer or VPS is you get persistent storage for free. Containers, however, are inherently ephemeral, meaning data generated within them is lost upon deletion. Fear not, though — the Sandbox SDK provides the sandbox.mountBucket() that you can use to automatically, well, mount your R2 bucket as a filesystem partition when the container starts.

Once we have a local directory that is guaranteed to survive the container lifecycle, we can use that for Moltbot to store session memory files, conversations and other assets that are required to persist.

AI agents rely heavily on browsing the sometimes not-so-structured web. Moltbot utilizes dedicated Chromium instances to perform actions, navigate the web, fill out forms, take snapshots, and handle tasks that require a web browser. Sure, we can run Chromium on Sandboxes too, but what if we could simplify and use an API instead?

With Cloudflare’s Browser Rendering, you can programmatically control and interact with headless browser instances running at scale in our edge network. We support Puppeteer, Stagehand, Playwright and other popular packages so that developers can onboard with minimal code changes. We even support MCP for AI.

In order to get Browser Rendering to work with Moltbot we do two things:

• First we create a thin CDP proxy (CDP is the protocol that allows instrumenting Chromium-based browsers) from the Sandbox container to the Moltbot Worker, back to Browser Rendering using the Puppeteer APIs.

• Then we inject a Browser Rendering skill into the runtime when the Sandbox starts.

From the Moltbot runtime perspective, it has a local CDP port it can connect to and perform browser tasks.

Next up we want to protect our APIs and Admin UI from unauthorized access. Doing authentication from scratch is hard, and is typically the kind of wheel you don’t want to reinvent or have to deal with. Zero Trust Access makes it incredibly easy to protect your application by defining specific policies and login methods for the endpoints. 

^{Zero Trust Access Login methods configuration for the Moltworker application.}

Once the endpoints are protected, Cloudflare will handle authentication for you and automatically include a JWT token with every request to your origin endpoints. You can then validate that JWT for extra protection, to ensure that the request came from Access and not a malicious third party.

Like with AI Gateway, once all your APIs are behind Access you get great observability on who the users are and what they are doing with your Moltbot instance.

Demo time. We’ve put up a Slack instance where we could play with our own instance of Moltbot on Workers. Here are some of the fun things we’ve done with it.

We hate bad news.

Here’s a chat session where we ask Moltbot to find the shortest route between Cloudflare in London and Cloudflare in Lisbon using Google Maps and take a screenshot in a Slack channel. It goes through a sequence of steps using Browser Rendering to navigate Google Maps and does a pretty good job at it. Also look at Moltbot’s memory in action when we ask him the second time.

We’re in the mood for some Asian food today, let’s get Moltbot to work for help.

We eat with our eyes too.

Let’s get more creative and ask Moltbot to create a video where it browses our developer documentation. As you can see, it downloads and runs ffmpeg to generate the video out of the frames it captured in the browser.

We open-sourced our implementation and made it available at https://github.com/cloudflare/moltworker, so you can deploy and run your own Moltbot on top of Workers today.

The README guides you through the necessary setup steps. You will need a Cloudflare account and a Workers Paid plan to access Sandbox Containers; however, all other products are either entirely free (like AI Gateway) or include generous free tiers that allow you to get started and scale under reasonable limits.

Note that Moltworker is a proof of concept, not a Cloudflare product. Our goal is to showcase some of the most exciting features of our Developer Platform that can be used to run AI agents and unsupervised code efficiently and securely, and get great observability while taking advantage of our global network.

Feel free to contribute to or fork our GitHub repository; we will keep an eye on it for a while for support. We are also considering contributing upstream to the official project with Cloudflare skills in parallel.

We hope you enjoyed this experiment, and we were able to convince you that Cloudflare is the perfect place to run your AI applications and agents. We’ve been working relentlessly trying to anticipate the future and release features like the Agents SDK that you can use to build your first agent in minutes, Sandboxes where you can run arbitrary code in an isolated environment without the complications of the lifecycle of a container, and AI Search, Cloudflare’s managed vector-based search service, to name a few.

Cloudflare now offers a complete toolkit for AI development: inference, storage APIs, databases, durable execution for stateful workflows, and built-in AI capabilities. Together, these building blocks make it possible to build and run even the most demanding AI applications on our global edge network.

If you're excited about AI and want to help us build the next generation of products and APIs, we're hiring.