Who should use Display Window Size?

Display Window Size is an open-source project built for web developers and browser users.

Does Display Window Size have a free plan?

Yes — Display Window Size is open source under the Open Source license and free to use.

What platforms does Display Window Size run on?

Display Window Size runs on the web, embeddable surfaces, macOS, Windows, and Linux.

Is Display Window Size still maintained?

Unverified. Display Window Size has not been re-checked since it entered the index, so there is no finding either way — and only a positive finding would say otherwise.

What are alternatives to Display Window Size?

Similar projects tracked by PulseGate include Web View Size, Window Resize, and Screen Sizer.

Who develops Display Window Size?

Display Window Size is developed by 123B.

When did Display Window Size launch?

Display Window Size first shipped in 2024.

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Display Window Size

Name: Display Window Size
Author: 123B

mozilla.orgBrowser DevTools & extensions

Display Window Size is an open-source Firefox extension that shows the current dimensions of the browser window. It helps web developers and other users check viewport sizing while adjusting or testing webpage layouts.

Open SourceWebEmbeddablemacOSWindowsLinux

Visit mozilla.org

Overview

4 features

In the Browser DevTools & extensions space, Display Window Size takes a focused approach. It focuses on checking browser window dimensions while testing and adjusting webpage layouts. It is built as an open-source project for web developers and browser users. The project is open source (Open Source). It runs on the web, embeddable surfaces, macOS, Windows, and Linux.

Behind Display Window Size is 123B, and it first shipped in 2024. Key capabilities include window size display, browser dimensions, and responsive testing. The interface is available in 32 languages, including Czech, German, and Greek.

Summary written by a language model from the project’s public pages.

Window size display
Browser dimensions
Responsive testing
Firefox toolbar access

Built with & integrations

Runs on

BrowserEmbeddablemacOSWindowsLinux

Trust & compliance

License

Open Source

Verified signals

HTTPSPrivacy Policy Terms of ServiceOpen SourceFree tierMulti-languageStore-verified publisher

Legal

Indexing history

What PulseGate has recorded for this listing

Indexed14 Sep · 16:22 UTC
Display Window Size verified via Firefox Add-ons
Source: Firefox Add-ons · Open

Frequently asked questions about Display Window Size

What does Display Window Size do?: Display Window Size focuses on checking browser window dimensions while testing and adjusting webpage layouts. It is catalogued under Browser DevTools & extensions on PulseGate.
Who should use Display Window Size?: Display Window Size is an open-source project built for web developers and browser users.
Does Display Window Size have a free plan?: Yes — Display Window Size is open source under the Open Source license and free to use.
What platforms does Display Window Size run on?: Display Window Size runs on the web, embeddable surfaces, macOS, Windows, and Linux.
Is Display Window Size still maintained?: Unverified. Display Window Size has not been re-checked since it entered the index, so there is no finding either way — and only a positive finding would say otherwise.
What are alternatives to Display Window Size?: Similar projects tracked by PulseGate include Web View Size, Window Resize, and Screen Sizer.Web View Size Window Resize Screen Sizer
Who develops Display Window Size?: Display Window Size is developed by 123B.
When did Display Window Size launch?: Display Window Size first shipped in 2024.

At a glance

Pricing: Open Source
Platforms: Web
License: Open Source
Built for: web developers and browser users
Model: Open source
Solves: Checking browser window dimensions while testing and adjusting webpage layouts.

Registered as

Firefox Add-ons: display-window-size

Developer

123B

Index record

Indexed: 14 Sep 2026
Lifecycle: Alive
Last seen: 14 Sep 2026

Identity audit (13)

Slug: display-window-size-mozilla-org
Lifecycle state recorded: 14 Sept 2026
Verification state: Indexed for public listing
Listing state: Listed: yes
Index status: Included in index
Latest evidence snapshot: 14 Sept 2026
Timeline basis: Indexed-at chronology. This listing's first-seen date was written by the catalog backfill, not observed here, so it is not treated as a sighting.
Name from: Derived from the project's own page and URL.
Category from: Assigned by a language model.
Summary from: Written by a language model from public pages.
Languages from: Detected by a language model, checked against the page's own declaration.
Last updated: 14 Sept 2026
Canonical URL: https://addons.mozilla.org/en-US/firefox/addon/display-window-size

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