How to aggregate content?


I would like to aggregate information from outside sites. 

Especially numbers, with which I will do different mathematical operations.

Do you know which is the most reliable solution to use? 

In Drupal 7 there was a function provided natively, but with drupal 8 you have to install the module feeds, or is there a solution already present?

Thanks in advance

(I will use either drupal 7 or drupal 8 depending on the solution)

Drupal version: