Preview web apps
See an app your agent is building, instantly — a live, throwaway preview of its dev server, no deploy required.
When an agent is building a web app, you want to see it running — not wait for a deploy. An App preview does exactly that: a live, throwaway view of the dev server running inside the agent's cloud computer. It's the fastest feedback loop between "the agent is building" and "this looks right."
How a preview happens
You don't deploy anything — the agent does it for you. While building, the agent starts a dev server on a port and requests a signed preview URL for it. That URL opens the running app in the workbench Browser, and Buda records the app so you can find it again.
The agent serves the app
The agent runs your app's dev server in its cloud computer and requests a preview URL for the port it's listening on.
Open the preview
The preview opens in the workbench Browser — interact with the live app right there. Preview URLs are short-lived; a fresh one is issued whenever you open the app again.
Jump back any time
Every preview is listed in Space settings → Apps & Sites and in the Commander Apps view. Selecting one re-requests a fresh URL, relaunches the preview, and jumps you to the session that owns it — so you pick up exactly where the app was last built.
Apps vs Sites
These look similar but solve different jobs:
| App preview | Site | |
|---|---|---|
| Purpose | See work-in-progress, instantly | Ship to the public |
| URL | Short-lived signed preview | Permanent public address |
| Lifetime | Tied to the running dev server | Deployed and persistent |
| Open action | Relaunch in the workbench Browser | Open the public URL |
| Plan | Every plan (preview is free) | Paid plans |
In short: preview while building, publish a Site when it's ready.
Because a preview URL is short-lived, it's for reviewing — not for sharing publicly. When you want a stable link, publish a Site.