Our firewall protects your privacy by automatically blocking trackers in the background when using other apps on your device. At the moment, this feature is available in the iOS version of 1Blocker because the necessary tools are supported by iOS only.
Trackers collect as much information about you as possible. It then can be sold to third-party companies or stored for future use. The information collected usually contains your personal data, such as your interests, your location, and so on.

Firewall prevents app trackers from even connecting to the Internet. Everything is done locally on your device only, so Firewall acts as a local proxy between you and the Internet. When it sees a request is being sent to a block-listed host, the extension just drops the connection. Other requests stay untouched and work just like before.
1Blocker installs a local VPN profile to perform on-device security checks of all internet connections other apps make. No traffic or data is sent to our servers. Firewall blocks outgoing network traffic to some domains using open-source domain lists maintained by the filter community. It operates at the network level, so you will stay protected no matter what app you use.

Firewall offers three filtering modes: Auto, DNS Proxy, and HTTP Proxy. They can be accessed from the (...) button located at the top-right corner of Firewall. We recommend using the Auto mode as it switches between DNS and HTTP modes automatically.

Another section that you may find useful is Recent Activity, which provides an overview of the tracking requests blocked by Firewall.

For more information, please, check the corresponding section of our Help Center here: Firewall FAQ