Some ad blockers, like uBlock Origin, are open source, so you can examine the code and see what they're doing: https://github.com/gorhill/uBlock https://github

Some ad blockers, like uBlock Origin, are open source, so you can examine the code and see what they're doing: https://github.com/gorhill/uBlock https://github.com/gorhill/uBlock The basic algorithm is to match URLs of loadable resources (images, JavaScript files, iframes, etc.) against huge lists of ad/malware/tracking sites. If the URL matches, the resource isn't loaded. The lists that uBlock Origin uses are enumerated here: https://github.com/gorhill/uBlock/blob/master/README.md https://github.com/gorhill/uBlock/blob/master/README.md