AdGuard
AdGuard Software Limited develops ad blocking and privacy protection software. Some of AdGuard's products are open-source, some are free, and some are shareware. AdGuard's DNS app supports Microsoft Windows, Linux, macOS, Android and iOS. AdGuard is also available as a browser extension.

AdGuard Software Limited was founded in 2009 in Moscow. In 2014 the company was incorporated in Cyprus and subsequently moved its headquarters there.

Products 

AdGuard products include:

AdGuard Home 
AdGuard Home acts as a recursive DNS resolver, which responds with an invalid address for domains that appear in its filter lists quests. It is similar to Pi-hole.

AdGuard Browser extensions 
The browser extension blocks video ads, interstitial ads, floating ads, pop-ups, banners, and text ads. There is a possibility to handle anti-AdBlock scripts. The product also blocks spyware and warns users of malicious websites. AdGuard Content Blocker is an additional browser extension for browsers Yandex Browser and Samsung Internet, which uses Content Blocker API. It downloads filter list updates and asks browsers to enforce them via Content Blocker API.

AdGuard applications 
AdGuard has Windows and Mac versions, as well as native mobile versions for Android and iOS. The application sets up a local VPN, which filters all traffic on the mobile device.

AdGuard DNS 
AdGuard hosts free public DNS servers. Some of these servers provide DNS-level network filtering for blocking domains used for delivering advertisement, online tracking, analytics. The product supports encryption technologies, including DNSCrypt, DNS over HTTPS, DNS over TLS and DNS-over-QUIC. AdGuard DNS also comes with an optional "Family Protection" mode for blocking access to websites with adult content as well as enforcing safe search in search engines. AdGuard began testing DNS service back in 2016, and officially launched it in 2018.

Reception 
While the company's products have earned positive feedback in industry publications, a series of policies by Google and Apple app stores occurred in 2014 - 2018, which impeded user access to AdGuard's mobile applications.

Macworld mentioned AdGuard for iOS in a list of five "best adblockers for iOS".

In April 2020, Android Central stated that AdGuard uses "a little more processing power to do its thing than uBlock Origin", but it is "the best all-in-one blocking tool for someone who doesn't want to use more than one extension" because it blocks cryptomining. However, Android Central recommended uBlock Origin with a dedicated cryptomining blocker over AdGuard.

Research 
AdGuard developers have taken up research in order to inform wider audiences on user privacy, cybersecurity and data protection. The following issues are notable cases involving the developers:

 Top-ranked websites involved in cryptojacking
 Facebook Ad Network widespread distribution
Fake adblockers
 Popular Android and iOS app privacy issues

Incidents 
 Distribution of AdGuard for Android was discontinued by Google Play at the end of 2014. It nevertheless is still being updated and has been made available for download from the developers’ own website.
 AdGuard for iOS has not been updated since the summer of 2018 due to Apple policies against ad blocking, though it was still present in the Apple App Store. In summer 2019, access to the updates of AdGuard's earlier edition for iOS was restored.
 In September 2018, AdGuard was hit by credential stuffing attack. AdGuard claims that their servers were not compromised and instead attackers used credential pairs reused by victims on other sites and stolen from those other sites. According to company spokesperson, they "do not know what accounts exactly were accessed by the attackers", so the company had reset passwords for all accounts "as a precautionary measure". Also, AdGuard pledged to use "Have I Been Pwned?" API to check all new passwords for appearance in known public data leaks. Furthermore, they implemented a more strict password security requirements.
In November 2020, Microsoft Edge Store was infiltrated with fraudulent add-ons resembling add-ons for AdGuard VPN and few security products.

References 

Ad blocking software
Android (operating system) software
IOS software
Privacy software
2009 software
Free and open-source software
Shareware