Thousand Sandbox documentation

Thousand Sandbox makes an exact working copy of a web app, as a sandbox for testing AI agents.

You point it at a web app you can log in to. It records the app while it is used, then runs a local copy that serves the app's own pages and scripts at the app's own addresses. Your agent works in the copy: no client access needed, nothing real gets changed, and a reset takes under a second.

It runs on your machine and sends nothing anywhere. The only outside call is to Anthropic, with your own API key, and only when you run sandbox build.

Where to start

If you want to	Read
See every part working on a bundled test app, with no account and no API key	Tutorial
Use it on an app of your own	Guide
Have an AI agent install, run or test it	For AI agents
Know what is finished and what is not	Status

Install

You need Node 22.13 or newer, pnpm 9 or newer, and Google Chrome.

git clone https://github.com/TomoKanazawa/thousand-sandbox.git
cd thousand-sandbox
pnpm install
pnpm build

The command is bin/sandbox in the clone. The Tutorial continues from here.

Status

Early. Everything in the tutorial works on the test app and passes its tests. It has not yet been run on a large real app. Status lists what is built and what is missing.

The code is open source under Apache-2.0, at github.com/TomoKanazawa/thousand-sandbox.