How to code a spying tool like adbeat ?

Hey,
I wanted to know if any of you knows how are spying tools like Adbeat, WhatRunsWhere coded ?

Thank you,

My guess is that they add a script to some code running on sites which advertisers are publishing on, which analyzes the behaviors of users and tries to predict using statistics what their tendencies are.

I tought they write a code to search on bing , adwords, etc ... some keywords and then they store the ads that are shown, i think they have many proxies so they can see the ads that are shown for each country. but i don't know how by doing that, they are sure to see all the ads ?
Hmm...Can you explain a litlle bit more what you said @https://www.blackhatworld.com/members/davinci-tech.1140711/, please ?

I think they scrape from cheaper providers of the same info and open a service

Doggy doggy world .

I think the legit way it all database subscription from advertising info provider ...

I'm not sure that I understood your question but i'll try and answer to the best of my understanding.

Ok lets say that you want to buy a car. so you go to a site called B to try and see which car is best for you. if B makes money from ads that it publishes from ad company A, then ad company A could run a script along with its ads that uses some kind of fingerprint technique to identify you across multiple sites. now lets say that you went to another site called C and C makes money by publishing ads from ad company A. then ad company A uses the fingerprint technique and infers that you visited B earlier from which it can conclude that you are interested in cars and show you car-related ads.

Very targetted and large scale scraping.

You really think ask this question can get you answer ? I doubt it.