Privacy addons for web browsers
This page helps users find free privacy-enhancing addons (i.e. plugins), and avoid addons that are non-free.
Finding free addons is sometimes hard because http://addons.mozilla.org/ hosts non-free addons alongside free addons, and doesn't even label them clearly (many just say "Custom Licence").
The GNUzilla project maintains a list of free addons here:
If you know of a free addon that isn't on that page, please send an email to bug-gnuzilla@gnu.org saying the name, the licence, and where it can be downloaded from.
When the page says an addon works with "Mozilla", this means Mozilla-based browsers including GNU IceCat, Iceweasel (in Debian), and Firefox.
Why you shouldn't trust non-free software such as Ghostery
Ghostery is now owned by Evidon (previously "Better Advertising"). As mentioned in this discussion, Ghostery's privacy policy states:
"We collect user traffic patterns (...) we track click-through information, including IP addresses (...) We may place a text file called a 'cookie' in the browser files of your computer. (...) We may provide personal information to or permit access to personal information by our vendors and service providers (...) If Evidon should ever file for bankruptcy, or have its assets sold to or merged with another entity, information Evidon receives from you, from the Website, is an Evidon asset and may be transferred."
If Ghostery was free software, someone could fork the software and publish a version which doesn't gather this data. Better yet, the original developers would know this, so they probably wouldn't put these nasty features in in the first place.
Updated information quoted from Wikipedia's Ghostery entry:
On March 8, 2018, Ghostery shifted back to an open source development model, citing that this would allow third-party contributions, as well as make the software more transparent in its operations. The company cited that Evidon's business model "was hard to understand and lent itself to conspiracy theories", and that its new monetization strategy would involve affiliate marketing and the sale of ad analytics data.