In a legal battle dating back more than three years, the court found in favour of Adblock Plus, an app developed by a firm called Eyeo and Axel Springer, which publishes Germany's best-selling daily Bild and also owns dozens of online portals.
Developed 10 years ago and downloaded hundreds of millions of times, the open-source software Adblock Plus is one of the most popular ad-blocking programmes, aimed at preventing intrusive adverts from popping up on the screen and tracking a user's search history for commercial ends.
But websites dependent on advertising revenue to remain free-of-charge see the open source software as a scourge.
In its ruling, the court found that “the programme does not violate the law against unfair competition.”
The judges ruled that the app did not interfere directly with Springer's ads.
“It is an autonomous decision of internet user to use the programme,” they argued.
Eyeo drew up a “white list” and a “black list” of sites depending on how intrusive their ads were.