There was a time when the only thing you would need to protect from viruses and malicious websites are your desktop computers or your laptops. But now that you're using mobile devices to browse the web more often than the more static devices, then your smartphones and tablets are also vulnerable to attacks. And when we say attacks, it's not just viruses, but rather the onslaught of unsolicited ads that bombard you when you visit websites, some of which can be harmful to your device.
Adguard is one of those apps whose main purpose is to filter your browser from all those ads, as well as the phishing websites, programs that will track your activity and other malicious sites. It will not affect the other apps that you use though because it will only filter the sites that you go to on your browser of choice. The way it works is that it can use two modes of traffic filtering: local VPN, which does not need root privileges, or local HTTP proxy mode, which is recommended if your device itself is rooted.
While the app is free, there are several features that you can avail when you pay their monthly fee. For example, they have a blacklist of millions of websites that are known for being malicious and phishing and this will supposedly never make it onto your browser. The ad filtering is also supposedly higher, plus you get the premium version of their tech support as well.
You can download Adguard for free from the Google Play Store and enjoy basic protection from those ads that prevent you from enjoying browsing through the inter-webs. But if you want the more stringent services, you need to pay a monthly, annual or bi-annual fee to ensure that those bad sites stay away from your gadgets.