What is Verklet

Verklet is a runtime that runs Node.js-style code inside a browser tab. It uses Web Workers for process isolation, WebAssembly for the heavy systems work, OPFS for persistent storage, and Service Workers for routing preview requests — so what your code produces is what your visitor sees.

It is distributed as @verklet/sdk, a single package you import into a client-side React, Vue, or vanilla project. Each integration uses a public projectId so Verklet can serve compatible runtime assets and registry URLs for the SDK version you installed. There is no backend to provision, no container to start, no SSH tunnel to keep open.

What you can build with it

• AI coding agents — give the agent a sandbox to mount, edit, and run code in, then surface the output back to the chat.
• Browser IDEs — bring your editor and a real runtime to the same origin. The terminal becomes just another component.
• Embedded tutorials — drop a working dev environment into your docs so the reader edits, the code runs, and the preview reloads.
• Customer demos — ship a live, mutable demo of your product without a backend to scale.

What you cannot use it for

• Workloads that need actual native binaries (Verklet runs WASM, not native syscalls — see browser support).
• Long-lived background jobs across page reloads (we persist filesystem state, not running processes).
• Anything that legally must run in your trust boundary, not the visitor's browser.

Ready? Jump to getting started.