# Mobile Simulator Extension MSIM: Responsive Viewer

> Professional mobile device simulator with multiple views, extensive device library, and sync scrolling

Canonical page: [https://chrome-stats.com/d/mobile-simulator-msim](https://chrome-stats.com/d/mobile-simulator-msim)

## Overview

- **ID:** `mobile-simulator-msim`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** Mobile Simulator (MSIM)
- **Category:** web-development,appearance
- **Daily users:** 22
- **Weekly downloads:** 13
- **Rating:** 5.00 / 5 (1 ratings)
- **Version:** 2.2.0
- **Last updated:** 2026-08-05
- **First published:** 2026-07-18
- **Size:** 38 KB
- **Data as of:** 2026-09-06
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/mobile-simulator-msim/)
- **Website:** [https://msim.app](https://msim.app/)

## Description

Mobile Simulator Extension: Responsive Viewer
Test, preview, and debug responsive designs across a massive library of mobile devices and tablets with the most powerful Mobile Simulator Extension on the Firefox Web Store.

🚀 Why Choose Mobile Simulator Pro?
Designing for the modern web requires testing across dozens of screen sizes. Mobile Simulator Extension: Responsive Viewer transforms your browser into a professional testing suite, allowing you to simulate any smartphone or tablet directly on your desktop.

📱 Extensive Device Library
Stop guessing how your site looks. Our Mobile Simulator provides high-fidelity frames for:

1) Apple iOS: iPhone 17 Pro / Pro Max, iPhone Air, iPhone 16 / 16 Pro, iPhone 15 series, classic models like iPhone SE, plus iPad Pro, iPad Air, and iPad Mini.
2) Android Suite: Samsung Galaxy S25, S24 Ultra, S23/S22, Google Pixel 9 / 9 Pro, Pixel 8 / 7, OnePlus 9, and Xiaomi Mi 11.
3) Tablets: iPad Pro 11 & 13 (incl. M4), iPad Air 13, Galaxy Tab S10, S9, and S8.
4) Custom Devices: Need a specific breakpoint? Use our Custom Device tool to enter any width and height.

🔥 Top Professional Features

Sync Scroll (Synchronized Scrolling): Scroll on one device and watch all other simulated screens follow in real-time. Perfect for side-by-side comparison testing.

Multi-View Mode: Open 2, 3, or 4 devices simultaneously to view your entire responsive grid at once.

Device Frames & Notches: See your website exactly as your users do, including hardware frames and screen notches for a realistic Mobile View.

One-Click Rotation: Instantly toggle between Portrait and Landscape modes to test orientation changes.

Quick Action Sets: Use pre-configured bundles like the "Popular 3-Pack" or "iOS Set" to speed up your workflow.

🛠 Built for Developers & Designers
Whether you are a web developer debugging a CSS issue or a designer performing a UX audit, this Responsive Viewer provides a seamless environment to ensure your site is mobile-friendly. It is the ultimate alternative to the native Firefox Developer Tools, offering a more visual and intuitive Mobile Simulator experience.

✅ Key Keywords Covered:
- Mobile Simulator Extension
- Responsive Viewer Firefox Extension
- Mobile View Extension
- Smartphone Simulator
- Device Simulator for Firefox

Transform your workflow today. Install the Mobile Simulator Extension: Responsive Viewer and build a better mobile web.

## Rankings

- #23,626 — Overall
- #28 — response
- #47 — mobile view
- #57 — mobile
- #126 — device
- #138 — ux

## Permissions and access

### Permissions

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

### Host permissions

- `http://*/*`
- `https://*/*`

## Safety

- **Risk impact:** Moderate risk impact
- **Risk likelihood:** High 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/mobile-simulator-msim)