Viewport resizer

Viewport resizer

Viewport resizer is a browser-based tool to test any website’s responsiveness. Just save the bookmarklet, go to the page you want to test, click on your created bookmarklet and check all kinds of screen resolutions of the page.

This bookmarklet should not replace a real device simulation. It rather helps you, your team and client testing statuses, transitions, text length etc. throughout different device types.


  • Full customization
  • Add and customize sizes on the fly
  • Manually orientation toggle by click (portrait | landscape)
  • Automatically device window orientation in “Auto Size” mode (portrait | landscape)
  • Media query support
  • Adapt meta viewport tag from current page
  • Manually page reload
  • Remove toolbar and land on current page
  • Viewport information (size, aspect ratio, orientation and user agent)
  • Touch-friendly
  • Vector-based
  • Online connection
  • JavaScript must be enabled
  • Note: Test page must be running inside frames, otherwise the toolbar has no chance to handle it.

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