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Responsive Design Tester

Preview websites at different device viewport sizes

iPhone SE375×667
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About this tool

Online responsive design tester — view any URL in preset device viewports from iPhone SE to Desktop, or enter a custom resolution. Scaled iframe preview with a device frame for rapid layout debugging.

responsive响应式viewportdevice设备mobilepreview

Frequently Asked Questions

What is Responsive Design Tester?
Online responsive design tester — view any URL in preset device viewports from iPhone SE to Desktop, or enter a custom resolution. Scaled iframe preview with a device frame for rapid layout debugging. This tool is part of the Dev Tools collection on ToolNext.
How do I use Responsive Design Tester?
Open this tool and paste or type your data into the input area. Click the action button to process your data. Results update in real time as you modify the input.
What programming languages or data formats does Responsive Design Tester support?
Responsive Design Tester broadly supports popular programming languages and common data formats. Whether you're a frontend or backend developer, you'll find the right processing capabilities here to boost your daily workflow.
What advantages does Responsive Design Tester have over local IDE plugins?
Responsive Design Tester requires no software or plugin installation — just open your browser and start using it. It's especially handy when you need to quickly process data, validate formats, or work on a device without a development environment.
Is Responsive Design Tester free to use?
Yes, Responsive Design Tester is completely free. All tools on ToolNext are provided free of charge — no registration required, no ads, and no hidden fees.
Is my data safe?
Absolutely. Responsive Design Tester processes all data locally in your browser. No data is ever sent to any server. Your data is cleared when you close the page.