# How to run ComputeSDK sandboxes on Runtime

Install `@computesdk/runtime`, pass `runtime()` as ComputeSDK's provider, and the same `compute.sandbox` code runs in a Firecracker microVM.

**On Runtime a ComputeSDK sandbox is a whole Linux machine billed on the CPU it uses.**
ComputeSDK is one TypeScript interface over many sandbox providers: E2B,
Modal, Vercel, Daytona and others, each its own package. The Runtime provider,
`@computesdk/runtime`, is published by ComputeSDK from its own repository and
built on Runtime's SDK, `withruntime`. Each sandbox is a microVM with its own
kernel, Ubuntu 24.04, Python, Node.js and `sudo`. The median sandbox answered
its first command 221 ms server-side after the create
request on 28 September 2026, and a 2 vCPU, 4 GiB sandbox costs $0.03125 an
hour while it waits. `@computesdk/runtime` 0.1.4 and `computesdk` 4.1.10 were
the current npm releases on 11 October 2026.

## Switch the provider

```bash no-run
npm install computesdk @computesdk/runtime
```

```js
import { compute } from "computesdk";
import { runtime } from "@computesdk/runtime";

compute.setConfig({ provider: runtime({ apiKey: process.env.RUNTIME_API_KEY }) });

const sandbox = await compute.sandbox.create({ metadata: { userId: "123" } });
try {
  const result = await sandbox.runCommand('python3 -c "print(\\"Hello World!\\")"');
  console.log(result.stdout); // Hello World!
} finally {
  await sandbox.destroy();
}
```

Nothing else in your code changes. Without `apiKey` the provider reads
`RUNTIME_API_KEY`, then the key `npx withruntime login` saved on the machine.

## Keep another provider as the fallback

ComputeSDK takes a list of providers and a strategy. With `priority` it tries
them in order, and `fallbackOnError` moves to the next when a create fails:

```js
import { compute } from "computesdk";
import { runtime } from "@computesdk/runtime";
import { e2b } from "@computesdk/e2b";

compute.setConfig({
  providers: [runtime(), e2b({ apiKey: process.env.E2B_API_KEY })],
  providerStrategy: "priority",
  fallbackOnError: true,
});
```

`compute.sandbox.create({ provider: "e2b" })` still picks one provider for a
single call.

## What each call does on Runtime

| ComputeSDK                            | On Runtime                                                                                   |
| ------------------------------------- | -------------------------------------------------------------------------------------------- |
| `create({ envs, metadata, timeout })` | `envs` on every command the provider runs, `metadata` as labels, `timeout` as the time limit |
| `create({ templateId })`              | Starts from a Runtime [image](/docs/images)                                                  |
| `create({ snapshotId })`              | Starts from a snapshot: files, memory and running processes                                  |
| `runCommand(cmd)`                     | `bash -c`, 60 seconds unless `timeout` says otherwise; past it, exit code 124                |
| `runCommand(cmd, { background })`     | Starts a Runtime process and returns at once                                                 |
| `onStdout`, `onStderr`                | Output as the command writes it, through the API; no port in the sandbox                     |
| `filesystem.*`                        | Runtime's file calls, not shell commands                                                     |
| `getUrl({ port })`                    | A private preview link carrying its token, one day by default                                |
| `destroy()`                           | Stops the sandbox; `getById` then returns `null`                                             |

`sandbox.getInstance()` returns the `withruntime` sandbox for what ComputeSDK's
interface leaves out: network rules, terminals, the desktop and pause.

## Where the other providers differ

ComputeSDK's README warns that "not every provider honors every option": some
pass `name`, `metadata` and `envs` through, some ignore them silently. The
Runtime provider maps all three. A sandbox reached later through `getById` or
`list` does not carry the `envs` given at create, because the provider object
that created it holds them; pass `env` to `runCommand` there.

Every account gets 100 free hours of a 1 GB machine every month, no card, and
runs four sandboxes at once without credit; with credit it runs
100, at $0.08 an hour for a 2 vCPU, 4 GiB sandbox with
both CPUs busy ([pricing](/docs/pricing)).

## Related

- [Runtime for ComputeSDK](/docs/computesdk), the provider's full options
- [Run untrusted LLM code](/use-cases/run-untrusted-llm-code)
- [Switch from E2B in one import](/how-to/switch-from-e2b-in-one-import)
- [Vercel AI SDK on Runtime](/integrations/vercel-ai-sdk)
- [What is a microVM?](/glossary/microvm)

## Sources

- [computesdk on npm](https://www.npmjs.com/package/computesdk), version 4.1.10, README read 11 October 2026
- [@computesdk/runtime on npm](https://www.npmjs.com/package/@computesdk/runtime), version 0.1.4 (10 October 2026), published from computesdk/computesdk `packages/runtime`

On 11 October 2026 `@computesdk/runtime` 0.1.4 ran against Runtime's API:
create, a command, streamed output, a file written and read, a timeout's exit
code 124, a background command, `list`, `getById` and `destroy`.

Facts on this page were checked on 11 October 2026.