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What is HTTPS filtering?
What is HTTPS filtering?
Written by James
Updated over a week ago

HTTPS filtering is a security mechanism employed by AdBlocker Ultimate to intercept and modify encrypted HTTPS traffic. This process is essential for effectively blocking ads on popular websites such as,, and, where ads cannot be removed without filtering HTTPS.

About HTTP(S)

HTTPS, short for HyperText Transfer Protocol Secure, is an enhanced version of the HTTP protocol that incorporates encryption measures to enhance security. Its primary purpose is to facilitate the secure transmission of sensitive information, such as personal data.

To understand the difference between regular HTTP and secure HTTPS, refer to the diagram below:

Understanding Certificates

Now that you're acquainted with HTTPS, let's address a critical question: how can you verify that you've established an encrypted connection with the intended website? This is where security certificates come into play. A certificate serves as proof that the website you're visiting is genuinely what it claims to be. Without a valid certificate or if the certificate contains incorrect information, your browser will prevent you from establishing a secure connection. It is crucial for a website's certificate to be issued by a trusted certificate authority (CA) recognized by your browser. Such a CA ensures that the SSL certificate is indeed issued to the rightful owner of the website.

Why AdBlocker Ultimate needs HTTPS Filtering?

In today's digital landscape, the majority of websites, including advertising platforms, have transitioned to HTTPS. This presents a challenge when it comes to ad-blocking. Many popular websites cannot have their ads removed without employing HTTPS filtering.

AdBlocker Ultimate filters HTTPS by establishing two secure connections when your browser attempts to connect to a server: one with the browser (or another app) and another with the server itself. The browser must trust AdBlocker Ultimate and the connections it establishes. To achieve this, AdBlocker Ultimate generates a unique root certificate and installs it into the system and certain browsers, such as Firefox. This allows AdBlocker Ultimate to monitor the contents of the secure connection and perform its primary function - blocking ads and trackers.

During the HTTPS filtering process, the browser's view of the website certificate is substituted with the certificate issued by AdBlocker Ultimate. While this may introduce limitations, AdBlocker Ultimate ensures that the original server's certificate is verified before deciding whether to filter the traffic or not. Additionally, AdBlocker Ultimate maintains a comprehensive list of exclusions for financial websites, payment systems, and sites handling sensitive personal data. Please can contact us to suggest additional websites for consideration.

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