---
title: "Preview Environments"
description: "How to set up, connect, and use preview environments in Baz"
---

Preview environments let Baz open your UI in a sandboxed browser, validate the ticket’s requirements, collect screenshots, and run full Spec Reviews.\
Without a working preview environment, Baz agents will fall back on a Spec Review focused on Code <> Ticket <> Design alignment.

**A preview environment is no longer the only way to give Spec Reviewer a running application.** With [sandboxed application review](/docs/capabilities/sandboxed-application-review), Baz launches the application from the Change branch itself inside a short-lived sandbox, so no Baz-accessible preview URL is required. Use a preview environment when you already deploy one per pull request, and sandboxed review when you would rather have Baz run the application.

This guide explains **what you need**, **how to connect it**, and **how to give Baz the correct preview URL** so everything works end-to-end.

### 1. What is a preview environment?

A preview environment is an internet-accessible instance of your deployed application for a specific pull request or branch.\
Examples:

* `https://cr-123.yourcompany.com`
* `https://vercel.app/pr-77`
* `https://feature-branch.preevy.dev`

Baz uses this environment to:

* Load your UI via Playwright
* Validate the behavior against the ticket
* Take screenshots of met/unmet requirements.

### 2. What _you_ need to provide

To make preview environments work with Baz, you need:

###  1. A deployable preview environment per PR

This can come from any platform:

* **Vercel Deploy Previews**
* **Netlify Preview Deploys**
* **GitHub Actions + Docker + any hosting**
* **Internal preview clusters** (if publicly accessible)

### 2. That preview environment must be reachable

Baz must be able to reach the URL from the public internet.

If your preview is behind a VPN or corporate firewall, you must allowlist Baz’s 3 outbound IPs:

```
18.190.165.140
3.20.124.148
3.12.220.91
```

### 3. Any required login credentials

If users must log in to see your app, Baz needs those credentials.

You configure them inside:\
**Settings → Integrations → Preview Environment**

### 3. Connecting your preview environment in Baz

### Step 1 - Open the integration panel

In Baz:\
**Settings → Integrations → Preview Environment → Configure**

### Step 2 - Enter the login credentials

This is only needed if your preview app is gated behind basic auth or a simple login screen.

* **User:** the username Baz should log in with
* **Password:** the password for that user

Click **Connect**.

If the credentials are valid, you’ll see the “Connected” state.

### 4. How Baz learns the preview URL

**You must give Baz agents the URL of the preview environment in the context of the pull request.**

Ideally, you do this by posting a comment on the GitHub PR.

### Option A - Your CI posts the URL automatically

This is the recommended approach.\
After deployment, CI adds a comment like:

```md
### Preview environment is ready
https://cr-1234.yourcompany.com
```

Baz reads this comment, validates the URL, logs in if needed, and starts Spec Review.

### Option B - You paste the URL manually

You can also comment manually on the PR:

<pre><code><strong>Baz run spec review. Preview URL: https://cr-4567.dev.myapp.com
</strong></code></pre>

Baz will detect it and run automatically.

## FAQ

<details>

<summary>Where do I get the “preview env URL”?</summary>

From your deployment system, not from Baz.\
Examples: Vercel/Netlify preview deploys, Preevy.dev links, a URL printed by your CI, or a hostname from your internal preview cluster. Once you have that URL, paste it in a PR comment (or have CI post it) and Baz will pick it up.

</details>

<details>

<summary>How do I change or remove the preview environment integration?</summary>

Go to Settings → Integrations → Preview Environment → Configure and overwrite the user/password if they changed. If you need the integration fully removed (for example, wrong env or org), contact Baz support; the UI will support delete soon.

</details>

<details>

<summary>How do I know everything is set up correctly?</summary>

Use this quick checklist:

* You can deploy your app to a public preview URL (or Baz’s IPs are allowlisted).
* You’ve configured preview-env credentials in Settings → Integrations → Preview Environment (if needed).
* Your CI or a developer posts the preview URL as a PR comment.

When these are in place, Baz will open the URL, authenticate, run Spec Reviewer, and add a report back to the PR.

</details>