1- AdBlock Plus
This is a useful extension that you can install on your browser and it actually blocks ads and pop-ups but it can also block tracking cookies and malware.
2- Ghostery
Ghostery™ sees the invisible web - tags, web bugs, pixels and beacons. Ghostery tracks the trackers and gives you a roll-call of the ad networks, behavioral data providers, web publishers, and other companies interested in your activity.
3-NoScript (Firefox) and ScriptSafe (Chrome, formerly ScriptNo)
Both disable all scripts from running on pages without you specifically adding them to an allow list. This includes Java, JavaScript, Flash, and others. They're powerful, but they're also really aggressive, and will break an awful lot of sites.
4- Flashblock
The extension automatically blocks flash content on webpages. Each flash element is being replaced with a placeholder that allows you to load only selected elements on a given page. You can also manage a whitelist of allowed websites via a configuration panel.
DoNotTrackMe is the new and improved DoNotTrackPlus. Now with more tracker blocking power, stop identity thieves, advertisers, social networks, and spammers from tracking you.
6- Disconnect
Disconnect lets you visualize and block the invisible websites that track you.
7- The Priv3
The Priv3 Firefox extension lets you remain logged in to the social networking sites you use and still browse the web, knowing that those third-party sites only learn where you go on the web when you want them to. All this happens transparently, without the need to maintain any filters. Priv3 is free to use for anyone
8- HTTPS Everywhere
HTTPS Everywhere is a Firefox and Chrome extension that encrypts your communications with many major websites, making your browsing more secure.
