Sandboxes

Check a sandbox from More > Sandbox Status in the Builder navigation.

Every app you open in the Builder runs in its own cloud sandbox. The sandbox holds your app’s code, installs its packages, runs the preview, and gives the AI agent a place to work. It starts when you open the app, so you don’t have to set anything up.

This page explains what you’ll see when a sandbox pauses, how to restart it, how many sandboxes your plan can run at once, and how to read the sandbox status.

When a sandbox pauses

Sandboxes pause after a period with no activity, which frees them for your other apps. Activity counts across the whole project: clicking, typing, or scrolling in any app in the project keeps all of the project’s sandboxes running.

1. When the project has been idle for a while, the Builder shows Are you still there? and a one-minute warning. Click Keep Working to keep the sandboxes running.
2. If nobody responds, the project’s sandboxes pause and the Builder shows Sandbox Paused.

Sandboxes also pause on their own after you leave the Builder, so you don’t need to stop them yourself.

Restart a paused sandbox

On the Sandbox Paused screen, click Restart Sandbox. The sandbox starts again and the app reloads, the same as when you first open it. Click Go to Dashboard if you’d rather leave it paused.

You can also open the app again later from your dashboard. Opening an app starts its sandbox.

Concurrent sandbox limit

Your plan sets how many sandboxes can run at the same time across your organization. Every app with a running sandbox counts, including your teammates’ apps. Paused sandboxes don’t count.

Plan	Sandboxes running at once
Free	1
Standard	1
Pro	Up to 3
Enterprise	Unlimited

When you reach the limit

If you open an app while your organization is already at its limit, the Builder shows Concurrent sandbox limit reached instead of the app. The message names your plan and its limit, for example: “You’ve reached your Pro plan’s limit of 3 concurrent sandboxes. Stop one running sandbox below to open this app.”

To open the app:

1. Under Running sandboxes, select the app you want to stop. Each one shows its name and when it was last active.
2. Click Stop and open this app. Draftbit stops the selected sandbox and starts the one for the app you’re opening.

Stopping a sandbox works like a pause, so check with your teammates before you stop one they might be using. You need the Editor role or higher to stop another app’s sandbox.

You can also:

• Click Retry to refresh the list and try opening the app again, for example after another sandbox pauses.
• Click View Plans to see plans with a higher limit.
• Click Go to Dashboard to leave without stopping anything.

Sandbox status

The Sandbox Status menu shows whether the sandbox is up and how far along each part of your app is. Open it from More at the bottom of the Builder navigation. The colored dot on the icon matches the overall status, and the same dot appears next to each app’s name on your project page.

The top line shows the overall status:

Status	Dot	Meaning
Started	Yellow	The sandbox is starting up.
Healthy	Green	The sandbox is running and ready.
Unhealthy	Red	The sandbox isn’t responding. Reload the Builder to restart it. If it stays red, ask for help from Get Help.
Stopped	Gray	The sandbox is paused or stopped. Opening the app restarts it.

Below that, the menu lists four parts of your app, each shown twice. Saved is the version from your last save, and Working is your working build, which includes your unsaved changes. See Comparing Builds for more on the two versions.

Item	What it tracks
Preview Server	The server that runs your app’s web preview.
Dependencies	Installing your app’s packages.
Project Files	Draftbit’s startup updates to your app’s project files.
Simulator Builds	The iOS and Android simulator builds.

Each item shows one of four icons:

• A checkmark means it’s done or running.
• A spinner means it’s still in progress.
• An X means it failed. Check Logs for the error.
• A dash means it hasn’t started yet. The saved preview and its packages can wait until you need them, and Simulator Builds shows a dash until you start a build.

Fix a stuck or broken preview

If the status shows a failed or stuck item, try these in order:

1. Click Restart Preview in the Builder navigation. It restarts the preview server without restarting the whole sandbox. If the preview has been starting for a long time, the button’s tooltip suggests this too.
2. Open Logs and look for the first error. A package that failed to install or a syntax error usually shows up there.
3. Ask the agent to fix the specific error you found, rather than asking it to “fix the preview.”

For more fixes, see Common Issues.