Web Preview

See a web app the Agent is running inside its sandbox — Buda turns its localhost link into a reachable preview URL.

When the Agent builds a website, demo, game, dashboard, or any frontend, you want to see it running. Web Preview does exactly that: the Agent starts the app inside its cloud computer, and Buda turns the sandbox localhost link into a preview URL you can open in your Local Browser.

An Agent running a preview

When to use it

Use Web Preview whenever the Agent runs something that serves a port. Just ask in plain language:

Start the dev server and give me the preview link.
Open the page in your Local Browser and check whether it works.

Basic flow

  1. Ask the Agent to run the app or start a preview.

  2. Wait for it to output a localhost link, e.g.:

    http://localhost:3000

  3. Click that link in the Buda page, or open your Local Browser (not AI Browser) and enter the link in the address bar.

  4. Buda converts the localhost link into an external preview URL — usually one ending in *.budaapps.com.

  5. Wait for that *.budaapps.com URL to load.

The same works for any port. Enter http://localhost:4000 in your Local Browser and Buda requests a preview for port 4000.

If the preview doesn't load

If the page is blank, stuck, or errors, ask the Agent to check the process and return a fresh link:

Please use /buda-web-preview to check the process and give me a working preview link.

If your Local Browser shows a WakeUp button, click it — Buda sends a restart/check request to the Agent and refreshes the preview after the service comes back.

Q&A

A *.budaapps.com URL says Unauthorized. What now?

Go back to your Local Browser and enter the original localhost URL again (e.g. http://localhost:3000). Buda requests a fresh signed preview URL and reopens it.

The preview shows Gateway Error.

The app process may not be running, or it's on a different port. Ask the Agent:

Please use /buda-web-preview to check the process and give me a preview link.

You can also click WakeUp to trigger the same recovery. See the buda-web-preview skill for details on this system-managed skill.

Do I need to know the start command?

Usually no. Tell the Agent what you want — "start this project and show me the web preview" — and it inspects the project, starts the right server, and returns the link.

On this page

When to use itBasic flowIf the preview doesn't loadQ&AA *.budaapps.com URL says Unauthorized. What now?The preview shows Gateway Error.Do I need to know the start command?Related pages