HighlightAll is an add-on for Firefox web browser which adds highlighting features. It is not meant to be a search tool, though.

You can leave feedback/suggestions or report issues using the contact link.

Caveat

For security reasons, Firefox extensions are blocked on some domains including the ones below. HighlightAll won't work on web sites in these domains. Check out https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Content_scripts for the full list.

Overview

HighlightAll makes it possible to highlight all occurrences of a word just by selecting it with the mouse.
Two modes are available:

 

Search markers

You can show search markers next to the scroll bar, which let you see where the searched terms are located in the page.
It is possible to go directly to the location by clicking on the marker:

Download

HighlightAll is hosted on addons.mozilla.org. You can download the latest stable version there:

Version history
HighlightAll v2.3 (November 25, 2020)
  • added "Match whole word" option (native mode)
  • added "Do not highlight selections containing only whitespaces" option (native mode)
  • added minimum number of characters option
  • automatic selection of black or white text color depending on highlighting color
HighlightAll v2.2.0 (August 25, 2018)
  • multiple color highlighting capability added
  • new option to keep highlighting upon click
HighlightAll v2.1 (March 4, 2018)
  • custom highlighting mode with search markers
  • added context menu item to trigger highlighting
HighlightAll v2.0 (November 4, 2017)
  • Full rewrite for Firefox 57+
  • Changing highlighting color, text selection behavior and keyboard shortcut is no more possible due to limitations in the new WebExtensions framework
HighlightAll v1.9 (December 27, 2016)
  • compatibility with Firefox 50+
  • added option to display or not the number of occurrences
  • added option for case sensitivity
  • desktop notification are used instead of status bar
HighlightAll v1.8 (November 1, 2015)
  • compatibility fixes for upcoming versions of Firefox
HighlightAll v1.7 (March 17, 2014)
  • compatibility with Firefox 27
HighlightAll v1.6 (February 5, 2012)
  • fixed problem of count of occurrences not showing up on Firefox 9 and 10
  • compatibility with Firefox 10.x
  • added Danish locale (thanks to Joergen)
HighlightAll v1.5 (September 26, 2010)
  • compatibility with Firefox 4.0
  • automatic highlighting of text is disabled when selecting several lines of text, so as to work around a limitation of Firefox's highlighting engine
  • findbar is cleared when unhighlighting if the "auto-fill" option is enabled
  • added options to change the highlighting color
  • added an option to copy the selected text to clipboard
  • highlighting now works with Firefox "Caret browsing" functionality
HighlightAll v1.4 (January 24, 2009)
  • added support for Firefox 3.1
  • added an option to specify a minimum number of characters to trigger highlighting
  • added an option to make Firefox stop the selection at punctuation when double-clicking a word
  • added support for "Auto Context" extension
  • new localizations : de-DE, hu-HU, nl-NL, pl-PL, pt-BR, tr-TR, zh-CN (many thanks to BabelZilla translators!)
HighlightAll v1.3.1 (March 10, 2008)
  • Added Japanese localization (thanks to goroneko & Naohiro)
HighlightAll v1.3 (January 13, 2008)
  • added support for Firefox 3
  • fixed dragging issue
  • added option to auto-fill the find field
HighlightAll v1.2 (February 28, 2007)
  • added a display of the number of occurrences in the status bar (warning: words in text boxes are not counted)
  • added an option to configure the keyboard shortcut
HighlightAll v1.1 (January 17, 2007)
  • backward compatibility with Firefox 1.5
  • added localization of the extension description
  • fixed a minor bug which prevented highlighting from being removed in some cases (but there are still the cases where Firefox is not itself able to remove it)

HighlightAll v1.0 (January 5, 2007)
Initial release