> For the complete documentation index, see [llms.txt](https://docs.testvibe.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.testvibe.com/runners.md).

# Where Runs Execute

When you start a run, TestVibe executes your tests against your project's URL. Every project has an **execution target** that decides *where* the test code runs and *how* the run reaches your application.

There are three targets. Most projects use the default and never change it.

## The Three Execution Targets

| Target              | Where test code runs                                                    | Use it when                                                                                                                                                       |
| ------------------- | ----------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Cloud** (default) | TestVibe's isolated cloud sandboxes                                     | Your site is reachable from the internet (public or staging). Nothing to install.                                                                                 |
| **Private runner**  | A runner you host inside your firewall                                  | Your app is fully private and must never leave your network. You run the runner image; the test code runs on your infrastructure.                                 |
| **Tunneled**        | TestVibe's isolated cloud sandbox, reaching a private app over a tunnel | Your app is private but you'd rather not host the runner. A small `tvtunnel` agent inside your network relays traffic; the test code stays in TestVibe's sandbox. |

{% hint style="info" %}
The cloud target is the default and the only one most teams need. Reach for a private runner or a tunnel only when the application under test is not reachable from the public internet.
{% endhint %}

## What You Can Do

<table data-view="cards"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>Understand cloud sandboxes</strong></td><td>Learn what a cloud sandbox is and how its lifecycle works.</td><td><a href="/pages/MFN5uxc0naidpR0m7lOv">/pages/MFN5uxc0naidpR0m7lOv</a></td></tr><tr><td><strong>Choose an execution target</strong></td><td>Decide whether a project runs in the cloud, on a private runner, or through a tunnel.</td><td><a href="/pages/nsuldvgQk3I0DUNc9MNw">/pages/nsuldvgQk3I0DUNc9MNw</a></td></tr><tr><td><strong>Host a private runner</strong></td><td>Run the runner image inside your firewall for fully private apps.</td><td><a href="/pages/JxKncfaujecnXzXqAyxN">/pages/JxKncfaujecnXzXqAyxN</a></td></tr><tr><td><strong>Set a project's default target</strong></td><td>Pick the execution target for a project and pin a tunnel device.</td><td><a href="/pages/njhHuzrg7J1AK5HMXUOY">/pages/njhHuzrg7J1AK5HMXUOY</a></td></tr><tr><td><strong>Fix execution issues</strong></td><td>Resolve unreachable sites, offline runners and tunnels, and runs stuck in preparing.</td><td><a href="/pages/U3R2iXfZUFCAHpMySmxw">/pages/U3R2iXfZUFCAHpMySmxw</a></td></tr></tbody></table>

## Related Help

* [What are cloud sandboxes?](/runners/what-are-runners.md)
* [Tunnel devices](/account-settings/tunnel-devices.md)
* [Understand live run status](/run-tests/understand-live-run-status.md)


---

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