From https://support.google.com/websearch/answer/86640

You may see "Our systems have detected unusual traffic from your computer network" if Google detects that a computer or phone on your network may be sending automated traffic to Google.

Automated traffic includes:

Sending searches from a robot, computer program, automated service, or search scraper Using software that sends searches to Google to see how a website or webpage ranks on Google

When this happens in Google Books, what are some possible criterions that Google Books or similar sites can use to detect that a compute may be sending automated traffic to their sites?

  • Your IP address is probably the major criteria. Things like User-Agent, lack of cookies/session id, etc, are probably secondary criteria. Using torproject.org may help
    – user5676
    Commented Nov 22, 2014 at 16:31
  • @barrycarter, I doubt it. Tor exit nodes get blocked very quickly by Google.
    – Nemo
    Commented Apr 20, 2015 at 22:42

1 Answer 1


Google uses complex anomaly detection systems, which are getting popularised with the NoCaptcha ReCaptcha.

Everything started with a mere counting of accesses, of course. You can have fun looking for more Google stuff.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.