How can you massively parse websites?

Question

Parsing

Tell me, how can I parse sites for the presence of a certain code / link on it?
Perhaps through services or own scripts on the server

Answer 1

own scripts on the server

Answer 2

Yandex and Google can find specific words on specific sites. If this is some kind of general task, use the help of search engines.

Answer 3

With the help of hands and head, however

Answer 4

Just like search engines do - with the help of a web crawler. He walks through sites, moving between them via hyperlinks - this method is good because you can scan absolutely everything to which there was at least some link somewhere.
Or you can scan the entire ipv4 range for a web server, feed each one to wget and find your link - this method is good because you can get to know Comrade Major very quickly. He, in turn, will help to change priorities in life and goals to more realistic and expedient.
Write down what you chose and what the result is! Very interesting.