# AdGuard

AdGuard is an ad blocking service for Microsoft Windows, Linux, MacOS, Android and iOS. AdGuard is also available as a browser extension.

## Features
### AdGuard Home

AdGuard Home acts as a recursive DNS resolver, which prevents most advertisements from displaying by responding with an invalid address for domains that appear in its filter lists. 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. It is also able to handle anti-AdBlock scripts. AdGuard blocks spyware and warns users of malicious websites. AdGuard Content Blocker is an additional browser extension for Yandex Browser and Samsung Internet, which uses Content Blocker API. It downloads filter list updates and requests 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 can set up a local VPN, filtering all traffic on the mobile device.

### AdGuard DNS

AdGuard operates recursive name servers for public use. AdGuard DNS supports encryption technologies, including DNSCrypt, DNS over HTTPS, DNS over TLS, and DNS over QUIC. AdGuard began testing DNS service back in 2016, and officially launched it in 2018.
| Server | Description |
| Default | Blocks advertisement and tracking domains. |
| Non-filtering | Does not block advertisement and tracking domains, or any other DNS requests. |
| Family protection | Blocks websites with adult content, enforces safe search in search engines wherever possible, and blocks advertisement and tracking domains. |

## History

During late 2014, the distribution of AdGuard's app for Android was removed from Google Play. It has since been made available for download from the developers’ own website.
From the summer of 2018 to the summer of 2019, AdGuard for iOS received no updates due to Apple policies at the time against ad blocking via the iOS VPN APIs.
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 more strict password security requirements.
In November 2020, Microsoft Edge Store and Chrome web store were infiltrated with fraudulent add-ons posing as various legitimate VPN browser add-ons, including NordVPN and AdGuard's VPN add-on. Subsequently Microsoft and Google were alerted and actions were taken to remove the fake add-ons in the various browser stores.

## Research

AdGuard developers have taken up research in order to inform wider audiences on user privacy, cybersecurity and data protection. The following issues are cases involving the developers:
* Websites involved in crypto jacking
* Facebook Ad Network widespread distribution
* Alerting or reporting of fake ad blockers
* Popular Android and iOS app privacy issues