# ScreenLab | Multi-Screen Preview

> Multiple screen preview for responsive web development - view pages at different device sizes, all synchronized

Canonical page: [https://chrome-stats.com/d/screenlab](https://chrome-stats.com/d/screenlab)

## Overview

- **ID:** `screenlab`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** Lucas
- **Category:** web-development
- **Daily users:** 11
- **Weekly downloads:** 2
- **Version:** 1.0.0
- **Last updated:** 2026-03-14
- **First published:** 2026-03-11
- **Size:** 154 KB
- **Data as of:** 2026-09-07
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/screenlab/)
- **Website:** [https://bitter.works](https://bitter.works/)

## Description

Stop wondering if your site looks right. Know it does.

Stop resizing your browser window over and over. ScreenLab lets you view any webpage across multiple device sizes simultaneously — no more guesswork, no more missed breakpoints.

🎯 One Click. Every Screen.
Toggle ScreenLab and instantly see your site rendered across phones, tablets, and desktops side by side. Test responsive layouts in real-time without leaving your browser.

📱 Pixel-Perfect Device Presets
iPhone, iPad, Android, MacBook, 4K monitors — all the devices your users actually use. Pre-configured viewport sizes so you can test what matters.

✨ Custom Viewports
Need a specific screen size? Create unlimited custom viewports. Save them for quick access across all your projects.

🔒 Lock Height Mode
Keep all screens contained within your viewport, or unlock to see full-page scrolling behavior. You control the view.

🔄 Synchronized Scrolling
Scroll once, scroll everywhere. All viewports stay perfectly in sync so you can compare sections across every breakpoint instantly.

📸 One-Click Screenshot Export
Capture all viewports at once and download as a ZIP. Perfect for design reviews, client presentations, or QA documentation.

🌙 Dark Mode Built In
Easy on the eyes during late-night debugging sessions. Toggle between light and dark themes instantly.

⚡ Works Everywhere
Chrome, Firefox — ScreenLab runs on all major browsers. Test any website, any URL, any time.

💎 Free plan with everything you need
Test up to 3 screens at the same time for free. Upgrade to our really cheap subscription-less "Plus" plan for unlimited viewports, custom presets, and screenshot exports.

## Rankings

- #32,490 — Overall
- #66 — preview
- #167 — screen
- #176 — review
- #187 — screen time
- #227 — response

## Permissions and access

### Permissions

- `activeTab`
- `scripting`
- `storage`

### Host permissions

- `<all_urls>`

### Content script matches

- `<all_urls>`

## Safety

- **Risk impact:** Moderate risk impact
- **Risk likelihood:** Moderate risk likelihood

### Analysis details

- Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
- This extension has low user count. Unpopular extensions may not be stable or safe.

> Some risk analysis details are omitted from this free response. [Upgrade to view the full analysis](https://chrome-stats.com/pricing).

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Source: [Chrome-Stats](https://chrome-stats.com/d/screenlab)