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

# Preview & Versions

The AI Builder live preview — desktop and mobile views, test versus live data, error detection with Ask to fix, and undoing or restoring earlier versions.

Each AI Builder project runs in its own **preview environment** — a private, working copy of your app, with its own server and database, that updates as the AI makes changes. It sits beside the chat, so you can try every change before publishing.

## Preview controls

| Control                   | What it does                                         |
| ------------------------- | ---------------------------------------------------- |
| **Desktop / Mobile view** | Switch the preview width to check responsive layouts |
| **Refresh preview**       | Reload the app                                       |
| **Open in new tab**       | Open the preview in its own browser tab              |
| **Fullscreen**            | Hide the chat and use the full window                |
| **View errors**           | List errors detected in the running app              |

The preview is fully interactive — sign up, submit forms, add to cart. It's for you, not your visitors: share the published address instead.

After a break, the preview can take a little longer to load the first time.

## Test data and live data

The preview has its own **test data**, separate from the **live data** of your published site. Records, accounts, and form submissions you create in the preview don't show up on the live site.

* On your **first** publish, the test database is copied to the live site as its starting data.
* On **later** publishes, only records that don't exist on the live site yet are added, so real visitors' data is left alone.

Test data is for trying things out and isn't backed up. See [Integrated Backend](/ai-builder/integrated-backend.md#test-and-live-data).

## Errors and Ask to fix

AI Builder watches the preview for errors. While building, the AI checks the result and fixes problems it finds. If something breaks later, you'll see **Errors were detected on your website**:

* **Ask to fix** sends the errors to the AI to analyze and fix. This uses AI credits.
* **View errors** shows the details first.

You can't publish while the preview has unresolved errors.

## Undo and restore

Every AI reply in the chat is a version of your project:

* **Undo this change** reverts the most recent change.
* **Restore this version** goes back to the project as it was after that message.

> **Note:** Restoring permanently removes all later messages and changes. It restores code and database structure, not database records, and credits used on the removed changes aren't refunded.

Restoring changes your project, not your live site — publish again to put the restored version live. Versions from before a project's structure was upgraded can't be restored.

## Related pages

* [Building with AI](/ai-builder/building-with-ai.md) — getting the result you want
* [Publishing & Domains](/ai-builder/publishing-and-domains.md) — taking the preview live
* [Integrated Backend](/ai-builder/integrated-backend.md) — test and live databases

***

*Last updated: October 20, 2026*