Run function on initial wordpress page request

[ad_1]

edit: Title should be **Run function on all wordpress page requests**

​

Hi,

I want to run a function before a wordpress page loads. The function will send a get request to an external source. The api response will then dictate which page a user sees. i.e will rewrite the url

Question, is this possible in wordpress, if so how please? Or is this something that should be done in the CDN?

Thanks a bunch!

[ad_2]