# Polypane vs Sizzy vs MobileViewer: Multi-Device Preview Tools
Choosing the right multi-device preview tool comes down to whether you need advanced features or just fast, simple testing. Polypane and Sizzy are premium desktop applications built for professional developers with advanced debugging, accessibility testing, and team collaboration features. MobileViewer is a free Chrome extension focused on instant multi-device testing without complexity. This guide compares all three so you can decide which tool fits your workflow, budget, and testing requirements.
## Key Takeaways
Here are the most important differences between Polypane, Sizzy, and MobileViewer.
– MobileViewer is completely free with no paid tiers or usage limits
– Polypane and Sizzy are premium tools starting at $12-$16 per month
– MobileViewer works directly in Chrome as a browser extension
– Polypane and Sizzy are standalone desktop applications with more features
– MobileViewer is best for designers and developers who need fast, simple testing
– Polypane offers the most comprehensive feature set including accessibility and SEO tools
– Sizzy focuses on developer workflow with hot reloading and element inspection
– Most individual developers and small teams do not need paid tools for responsive testing
## What to Look for in a Multi-Device Preview Tool
The best tool for you depends on your priorities and budget.
– **Cost:** Can you justify a monthly subscription or do you need a free option?
– **Feature depth:** Do you need advanced features like accessibility testing and SEO audits, or just viewport previews?
– **Ease of access:** Do you want a tool in your browser or are you okay opening a separate desktop app?
– **Team collaboration:** Do you need features for sharing previews or collaborating with teammates?
– **Performance:** Does it run smoothly without consuming excessive system resources?
– **Learning curve:** Can you start using it immediately or does it require training?
– **Workflow integration:** Does it fit into your existing development process or require changing how you work?
## 1. MobileViewer
MobileViewer is a free Chrome extension that shows your website across multiple device viewports at once. It works directly in your browser so there is no download, installation, or configuration. You click the extension icon and instantly see your site on iPhone, iPad, Android, and desktop viewports side by side. The tool is designed for speed and simplicity, focusing on the most common responsive testing use case without adding complexity.
The extension integrates seamlessly with your existing browser workflow. You can test localhost URLs, use Chrome DevTools on any viewport, and switch between devices with one click. Because MobileViewer runs entirely in the browser, it launches instantly and uses minimal system resources. There is no separate app to open, no updates to manage, and no account to create.
MobileViewer stands out because it removes all friction from responsive testing. Most developers and designers just need to see if their layout breaks on mobile and tablet viewports. MobileViewer does exactly that in the simplest way possible. You install it once and it is always available in your browser toolbar.
If you want a responsive testing tool that feels invisible until you need it, works instantly, and never gets in the way, MobileViewer is the right choice. It prioritizes speed and simplicity over advanced features that most people never use. Best of all, it costs nothing and has no usage limits.
### Key Features
Here is what makes MobileViewer the best free multi-device preview tool.
– **Instant multi-device preview:** See your site on multiple viewports simultaneously without switching tabs
– **No signup required:** Install from Chrome Web Store and start testing immediately
– **Localhost testing:** Test local development environments before deploying
– **Custom viewports:** Add any screen size or device you need for testing
– **Screenshot capture:** Take screenshots of each viewport for bug reports or design reviews
– **Chrome DevTools integration:** Use full DevTools functionality on any viewport
– **Completely free:** No paid plans, trial limits, or premium features
– **Zero configuration:** No setup, no account, no learning curve
### Pricing
MobileViewer is completely free. There are no paid plans, usage limits, or premium features.
## 2. Polypane
Polypane is a premium desktop application designed for professional web developers and agencies. It provides multi-device previews with advanced features including accessibility testing, SEO audits, meta tag validation, and performance monitoring. Polypane displays your site across multiple viewports with synchronized scrolling, clicking, and navigation. The app also includes built-in tools for testing color contrast, simulating vision deficiencies, and validating semantic HTML.
Polypane is the most feature-rich option in this comparison. It goes beyond simple viewport testing to include accessibility compliance, social media preview testing, and detailed debugging tools. The app is built for teams and professionals who need comprehensive testing features in one place. It runs as a standalone Electron app on Windows, macOS, and Linux.
Polypane makes sense for agencies, large teams, or developers who need advanced features like accessibility audits and SEO validation alongside responsive testing. However, it is expensive compared to free tools, and most of its advanced features are rarely needed by individual developers or small teams focused on basic responsive testing.
### Key Features
Here is what Polypane offers for professional web development.
– **Multi-viewport preview:** Display multiple devices simultaneously with synchronized interactions
– **Accessibility testing:** Built-in tools for color contrast, ARIA validation, and semantic HTML checks
– **Vision deficiency simulation:** Test how your site looks for users with color blindness or low vision
– **SEO and meta tag validation:** Check Open Graph, Twitter Cards, and other meta tags
– **Performance monitoring:** Track page load times and resource usage across viewports
– **Screenshot and sharing tools:** Capture and share previews with team members
– **Hot reloading:** Automatically refresh when files change during development
– **Element inspection:** Built-in DevTools for debugging
### Pricing
Polypane starts at $12 per month (billed annually) or $16 per month (billed monthly). A free trial is available.
## 3. Sizzy
Sizzy is a premium desktop application focused on developer workflow and multi-device testing. It displays your website across multiple device viewports with synchronized scrolling, clicking, and navigation. Sizzy emphasizes speed and developer experience with features like hot reloading, element inspection, and custom device profiles. The app is designed to replace browser DevTools for responsive testing.
Sizzy offers a clean, modern interface with strong developer-focused features. It includes built-in DevTools, screenshot capture, and the ability to add custom user agents and viewport sizes. The app performs well with multiple viewports open and provides keyboard shortcuts for fast navigation. Sizzy is best for developers who want a dedicated responsive testing environment with more power than browser extensions but less complexity than Polypane.
Sizzy is a middle-ground option between MobileViewer’s simplicity and Polypane’s comprehensive feature set. It provides advanced testing features without the accessibility and SEO tools that Polypane includes. However, it still costs money, and for many developers, the features it offers do not justify the subscription price compared to free alternatives.
### Key Features
Here is what Sizzy provides for multi-device testing.
– **Synchronized interactions:** Scroll, click, and navigate across all viewports at once
– **Hot reloading:** Automatically refresh when code changes
– **Built-in DevTools:** Inspect elements and debug within the app
– **Custom device profiles:** Create and save viewport sizes and user agents
– **Screenshot tools:** Capture full-page or viewport-specific screenshots
– **Keyboard shortcuts:** Fast navigation and viewport switching
– **Modern interface:** Clean, intuitive design built for developers
– **Cross-platform:** Available for Windows, macOS, and Linux
### Pricing
Sizzy costs $15 per month or $120 per year. A free trial is available.
## Polypane vs Sizzy vs MobileViewer: Feature Comparison
All three tools solve the same core problem but differ significantly in approach, features, and cost.
**Cost:**
– MobileViewer wins decisively. It is completely free with no paid tiers. Polypane costs $12-$16 per month. Sizzy costs $15 per month. For individual developers and small teams, free is hard to beat.
**Ease of Access:**
– MobileViewer is the fastest to access. It lives in your browser and launches instantly. Polypane and Sizzy are desktop applications that require opening a separate app every time you test.
**Feature Depth:**
– Polypane has the most features, including accessibility testing, SEO audits, and vision deficiency simulation. Sizzy focuses on developer workflow with hot reloading and DevTools. MobileViewer focuses solely on multi-device preview without extra complexity.
**System Resources:**
– MobileViewer is the lightest. It runs in your browser tab without adding a separate application. Polypane and Sizzy are Electron apps that use more memory and CPU.
**Workflow Integration:**
– MobileViewer integrates directly with Chrome and DevTools. You never leave your browser. Polypane and Sizzy run separately, which means switching between your editor, browser, and the testing app.
**Advanced Features:**
– Polypane and Sizzy offer synchronized interactions, hot reloading, and built-in DevTools. MobileViewer does not include these features but allows you to use Chrome DevTools on any viewport. For most developers, Chrome DevTools is sufficient.
**Learning Curve:**
– MobileViewer has no learning curve. Click the icon, see the viewports. Polypane and Sizzy have more features, which means more to learn and configure before you get value from them.
## When to Choose MobileViewer
MobileViewer is the best choice for designers, developers, and small teams who need fast responsive testing without cost or complexity.
Choose MobileViewer if:
– You want instant access to multi-device testing without leaving Chrome
– You need a free tool with no usage limits or paid tiers
– You prefer lightweight tools that do not consume extra system resources
– You already use Chrome DevTools and do not need a separate testing environment
– You test responsive layouts frequently and want a tool that stays out of your way
– You do not need advanced features like accessibility audits or SEO validation
– You are an individual developer or small team without a testing budget
MobileViewer is ideal for fast, simple responsive testing that fits seamlessly into your existing workflow. It does one thing extremely well without adding complexity or cost.
## When to Choose Polypane
Polypane is the best choice for agencies, large teams, or developers who need comprehensive testing features beyond responsive design.
Choose Polypane if:
– You need accessibility testing, SEO audits, and vision deficiency simulation
– You are building sites that must meet strict accessibility standards
– You want all testing tools in one application instead of using multiple separate tools
– You work on client projects that require detailed compliance and validation
– You can justify the monthly cost based on time saved and features provided
– You need team collaboration features and sharing tools
Polypane is ideal for professionals who need more than basic responsive testing and want a comprehensive testing suite in one place.
## When to Choose Sizzy
Sizzy is the best choice for developers who want advanced features like hot reloading and synchronized interactions without the full complexity of Polypane.
Choose Sizzy if:
– You want synchronized scrolling and clicking across all viewports
– You need hot reloading to automatically refresh when your code changes
– You prefer a dedicated testing environment separate from your browser
– You want more control than browser extensions offer but less complexity than Polypane
– You can justify the monthly cost for developer workflow improvements
– You do not need accessibility or SEO testing features
Sizzy is ideal for developers who want a middle-ground option between free browser extensions and comprehensive paid tools like Polypane.
## Conclusion
The right multi-device preview tool depends on your budget, workflow, and feature requirements. MobileViewer is the best choice for most developers because it is completely free, works instantly in your browser, and provides everything needed for fast responsive testing. It removes all friction from multi-device validation without adding cost or complexity.
Polypane is the best choice for professionals who need comprehensive testing features including accessibility audits, SEO validation, and vision deficiency simulation. It is expensive but provides the most complete feature set in one application.
Sizzy is a middle-ground option for developers who want advanced features like hot reloading and synchronized interactions without the full complexity and cost of Polypane.
For individual developers, freelancers, and small teams, MobileViewer provides 90% of what you need for 0% of the cost. Start with MobileViewer and upgrade to a paid tool only if you require advanced features that justify the monthly subscription.
## Frequently Asked Questions
**1. Is Polypane or Sizzy worth the cost?**
For most individual developers, no. Free tools like MobileViewer provide everything needed for responsive testing. Polypane and Sizzy make sense for agencies, large teams, or developers who need advanced features like accessibility testing or hot reloading.
**2. Can MobileViewer replace Polypane or Sizzy?**
For basic multi-device testing, yes. MobileViewer shows multiple viewports simultaneously and integrates with Chrome DevTools. It does not include advanced features like accessibility audits or synchronized interactions, but most developers do not need those features.
**3. Which tool is best for accessibility testing?**
Polypane is the best option for accessibility testing. It includes built-in tools for color contrast, vision deficiency simulation, and ARIA validation. MobileViewer and Sizzy do not include accessibility-specific features.
**4. Do I need a desktop app or is a browser extension enough?**
For most developers, a browser extension like MobileViewer is enough. Desktop apps like Polypane and Sizzy offer more features but add complexity and cost. Start with a browser extension and upgrade only if you need advanced features.
**5. Which tool is fastest for quick responsive checks?**
MobileViewer is the fastest because it works instantly in your browser without opening a separate application. You click the icon and see all viewports immediately.