Updated January 14, 2021. See this twitter thread for details.

Several Web Browser apps want to make it easier for people & teams to test and develop Responsive Websites and Web applications iteratively.

These apps are different from services that offer static screen captures of web pages across various popular browser versions and operating systems. Such browser snapshot services have been around for a while and are certainly a helpful tool – especially when trying to do QA for legacy browsers that you plan to support.

In contrast, these specialized Web Browser DevTools focus on allowing Front-end devs to see a realtime synchronized view of responsive web content scrolling within multiple viewport ‘panes’ simultaneously.

This approach enables a website builder to review and compare the same design across various screen dimensions. Scanning multiple renderings all at once can help a developer iteratively fine-tune their layout to perform well on different device sizes.

While this multi-view in a single app approach may never truly replicate testing on the native target devices, such a browser can help you improve your coded results much quicker than a device lab alone.

Here’s a roundup of these unique web content viewing solutions.

Blisk

Blisk is the first developer-oriented browser. It provides businesses with a development workspace for the teams and freelancers to develop and test modern web applications twice faster.”

Emmet Re:view

Emmet Re:view “A browser extension for displaying responsive web-pages in a side-by-side views to quickly test how it looks at different resolutions and devices.”

LT Browser by LambdaTest

LT Browser “Perform free automated and live interactive cross browser testing on 2000+ real browsers and real devices online.”

Polypane

Polypane “Improve your web dev workflow. All the tools you need to build responsive, accessible and performant sites five times faster.”

Responsively App

Responsively App “A dev-tool that helps with faster responsive web apps development. A must-have tool for all web developers. Free and Open Source!”

Sizzy

Sizzy “The browser for developers. Stop wasting time and speed up your development workflow.”

Here’s a copy of this list in an Airtable database that you can bookmark, follow or copy. If I missed any, please let me know or reply to this Twitter thread.