# What Are Cloud Sandboxes?

URL: https://docs.testvibe.com/runners/what-are-runners

A cloud sandbox is the environment that does the work when you start a run on the default execution target. TestVibe allocates an isolated sandbox for that run, prepares it automatically, executes your Playwright tests inside it, and tears it down afterwards.

You never install, register, or maintain anything — sandboxes are built for running AI-generated code safely, and each run gets its own.

## What A Sandbox Does

| Step | What happens | Load your project | The sandbox receives the selected tests and configurations from your project. | Prepare the environment | Browsers and test dependencies are set up automatically. | Run browser tests | Playwright opens your target site and follows the test steps. | Stream live status | Per-scenario and per-step status streams into the app while the run executes. | Upload evidence | Screenshots, videos, traces, console logs, and network details upload to TestVibe's cloud and appear in the Runs section. 

## Run Lifecycle

| State | Meaning | Queued | The run is waiting for a sandbox. | Preparing | A sandbox is being allocated and set up. | Running | Tests are executing; live status streams into the app. | Passed / Failed / Cancelled / Error | The run reached a terminal state and its evidence is available. 

For how this looks in the app, see [Understand live run status](/run-tests/understand-live-run-status) .

## Reaching Your Site

The cloud sandbox opens your site URL from TestVibe's cloud. Public and staging URLs work without any setup. If the application is private or internal, you have two options that don't change anything else about the run:

- Reach it through a [tunnel device](/account-settings/tunnel-devices) so the sandbox can dial inside your network, or
- Run the tests on a [private runner](/runners/self-hosted-runners) you host inside your firewall instead.
See [Choose an execution target](/runners/choose-a-runner) to decide which fits.

## Related Help

- [Choose an execution target](/runners/choose-a-runner)
- [Private runners](/runners/self-hosted-runners)
- [Understand live run status](/run-tests/understand-live-run-status)