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

Terminalnpm install computesdk @computesdk/runtime

JavaScriptimport { 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:

JavaScriptimport { 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
`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).

Runtime for ComputeSDK, the provider's full options
Run untrusted LLM code
Switch from E2B in one import
Vercel AI SDK on Runtime
What is a microVM?

Sources

computesdk on npm, version 4.1.10, README read 11 October 2026
@computesdk/runtime on npm, 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.