> ## Documentation Index
> Fetch the complete documentation index at: https://bruno-a6972042-mintlify-71caebff.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# JavaScript Sandbox

Bruno provides two modes for executing JavaScript code in your collections:

1. Safe Mode
2. Developer Mode

<img src="https://mintcdn.com/bruno-a6972042-mintlify-71caebff/CHP37XdxOf5nqjR6/v2/images/screenshots/javascript-sandbox.webp?fit=max&auto=format&n=CHP37XdxOf5nqjR6&q=85&s=04e4fecedea12b9798e83d0fa44a7b40" alt="Javascript Sandbox" width="2480" height="1130" data-path="v2/images/screenshots/javascript-sandbox.webp" />

## Safe Mode

JavaScript code is executed in a secure sandbox and cannot access your filesystem or execute system commands. We recommend Safe Mode for most users.

<Info>
  When in doubt, leave the Collection in Safe Mode. You can always switch to Developer Mode later.
</Info>

## Developer Mode

JavaScript code has access to the filesystem, can execute system commands and access sensitive information.

#### When to use Developer Mode

* You trust the collection source/authors (Ex: Collection maintained by you/your team) and Safe Mode is not enough for your use case.
* You need to use external npm packages in your scripts
* Your collection needs access to filesystem / system commands

#### When to avoid Developer Mode

* You are running a collection that you do not trust (Ex: Downloaded from the internet)

<Warning>
  Developer Mode can be dangerous and should only be used when you fully understand the implications.
</Warning>