Online advertising can be a divisive thing. On the one hand, ads support the free content model of the internet, subsidizing many of our favorite websites. But badly designed or intrusive pop-up ads can be disruptive and tracking cookies and similar advertising trackers raise many privacy concerns. The best ad blockers and anti-tracking software let you block irritating ads, save bandwidth, and opt out of intrusive marketing systems. In extreme scenarios, they can even block malicious ads that seek to infect your devices.
NOTE: Ad blocking takes away revenue from publications like the one you're reading and risk the ability of media to provide otherwise free content.
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AdBlock Plus (ABP) is among the most popular ad blockers, with versions available for Firefox, Chrome, Safari and Opera. ABP features a quick setup, loading preset filter lists that allow users to quickly block most ads, as well as the option to filter malware and social media buttons. Savvy users can chose additional block lists as well as set custom filters or whitelist their favorite sites to keep their ad revenue in the black. AdBlock Plus allows what it calls "non-intrusive advertising" through filters, which may irk some users, though this can be disabled in settings. On Android, the AdBlock Browser provides a Firefox-based browser that blocks incoming advertising, while on iOS, the AdBlock Plus app integrates with the content blocker system to seamlessly block advertising on Safari with minimal setup.
AdBlock (no relation to AdBlock Plus) is the other best ad blocker extension of note, available for users of Chrome, Opera and Safari. AdBlock uses a series of filter lists to automatically block ad content coming from known ad servers and providers. Users can stick with the default block lists, subscribe to additional ones, or even create their own, as well as whitelist their favorite websites. As one of the most downloaded Chrome and Safari extensions, AdBlock has the trust of many users worldwide.
AdBlocker Ultimate is a free browser-based ad blocker that makes a big deal about being beholden to no advertising companies, strictly letting no ads through. It also doesn't have any corporate sponsorships that let through whitelisted website ads. In addition, AdBlocker Ultimate also blocks known malware, adware, and tracking domains. The add-on is available for popular browsers like Chrome, Firefox, Safari and Opera.
Ublock Origin (Chrome, Firefox, Safari) is a browser-based ad blocker that focuses on simple, efficient blocking with a low resource overhead. The extension comes loaded with a number of filter lists for known advertising and malware sources, with extra filter lists available and the option to read and create your own custom filters from hosts files.
AdLock (Windows, Chrome, Android) avoids the browser-based route, and instead opting to run as a separate program to be able to block not only browser-based ads, but also advertising in other programs like Skype or games. The app runs in the background, using filters to block ads, popups, and autoplaying videos, speeding up loading times and applying Safe Browsing features to automatically block sites that are known to be unsafe. The mobile version, for obvious reasons, is unavailable on the Google Play Store, so you'll need to sideload the app if you want to get AdLock into your Android device.
Android users with a rooted device can check out AdAway, a free and open source ad-blocker that works on the host's file level, so that when an app or webpage makes a request to a particular ad provider, it instead goes to a blank IP address (127.0.0.1). That saves your bandwidth and keeps you from being spammed by advertising. AdAway lets you use hosts files from a variety of sources, or one of your making, with options to blacklist or whitelist particular addresses and add your own redirects. You will need to allow installing third party apps (or download AdAway through the F-Droid app), as AdAway isn't available in the Google Play store.
Firefox Focus (Android, iOS) is another addition to Mozilla's family of browsers. This one's a privacy-oriented version of Firefox that bakes in ad-blocking and anti-tracking into a light and functional package. Firefox Focus blocks ads and speeds up browsing, while also working in privacy-friendly features like automatic history and cookie clearing. Users can selectively block ads, analytics, content and social trackers with easy toggles, turn on a "stealth" mode, and set a default search engine.