Investigating the effectiveness of web adblockers

TL;DR

This study analyzes the durability of web adblocking filters over time, revealing that general filters slightly lose effectiveness after about 80 days, while specialized anti-adblocking filters remain stable.

Contribution

It provides empirical data on the temporal effectiveness of adblocking filters and compares general versus specialized filter longevity.

Findings

EasyList effectiveness decays by 0.13% daily

Effectiveness stabilizes after approximately 80 days

Specialized anti-adblocking filters show no significant decay

Abstract

We investigate adblocking filters and the extent to which websites and advertisers react when their content is impacted by these filters. We collected data daily from the Alexa Top-5000 web sites for 120 days, and from specific sites that newly appeared in filter lists for 140 days. By evaluating how long a filter rule triggers on a website, we can gauge how long it remains effective. We matched websites with both a regular adblocking filter list (EasyList) and with a specialized filter list that targets anti-adblocking logic (Nano Defender). From our data, we observe that the effectiveness of the EasyList adblocking filter decays a modest 0.13\% per day, and after around 80 days seems to stabilize. We found no evidence for any significant decay in effectiveness of the more specialized, but less widely used, anti-adblocking removal filters.