Display the X-Clacks-Overhead in Clacks Semaphore, including http-equiv meta tags. Forked from GNU_Terry_Pratchett

What is X-Clacks-Overhead?

X-Clacks-Overhead is a Firefox add-on that allows you to see and read the message included in the html header, as well as visually display it in semaphore style. It is a fork of the GNU_Terry_Pratchett extension and supports http-equiv meta tag detection.

Users: 281 ▼ -4
Rating: 5.00 (4)
Version: 0.4.1 (Last updated: 2019-01-05)
Creation date: 2019-01-05
Weekly download count: 2
Firefox on Android: No
Risk impact: High risk impact
Risk likelihood: Low risk likelihood
Manifest version: 2
  • webRequest
  • tabs
  • alarms
  • <all_urls>
Size: 610.35K
Stats date:

Other platforms

Not available on Chrome
Not available on Edge
Want to check extension ranking and stats more quickly for other Firefox add-ons? Install Chrome-Stats extension to view Chrome-Stats data as you browse the Firefox Browser Add-ons.
Chrome-Stats extension

This is a fork of the GNU_Terry_Pratchett extension, fixed to support http-equiv meta tag detection (as long as only one X-Clacks-Overhead meta tag is used). Thanks to IgnoredAmbience's review of the original extension for the required fix of changing "Document" to "document" in gnu.js.

Original description

In tribute to the late Sir Terry Pratchett many websites are adding the message "GNU Terry Pratchett" into the html header "X-Clacks-Overhead". This plugin allows you to see when a website is using the header and read the message included. The message is also displayed visually in the semaphore style from the upcoming board game "Clacks" by Backspindle Games.

Concept: Richard Atha-Nicholls Art: Amy Atha-Nicholls Coding: Rob Grundy

User reviews
I love this fork, because I serve some websites using HTTP/2 which forces lowercase header names. This extension—as opposed to the original—detects "x-clacks-overhead" correctly. (The original only checked for a case-sensitive "X-Clacks-Overhead" header, which isn’t allowed with HTTPS/2.)
View all user reviews
Risk impact

X-Clacks-Overhead is risky to use as it requires a number of sensitive permissions that can potentially harm your browser and steal your data. Exercise caution when installing this add-on. Review carefully before installing. We recommend that you only install X-Clacks-Overhead if you trust the publisher.

Risk likelihood

X-Clacks-Overhead has earned a fairly good reputation and likely can be trusted.

Upgrade to see risk analysis details