How legal is it to use a crawler?

Question

Programming

How legal is it to comb out information from sites and use it at home:

1. for internal needs
2. parade

?
For example, take the price of a phone from online store A and B, and set on the page what is cheaper in store A. What is the reaction of the owners likely to be?

Answer 1

Information about the product, its characteristics, price, warranty service, terms of exchange, return, delivery, etc. is part of the store's public offer.
You can easily take this information and publish it somewhere on your website / VK group / mailing list, etc.
Base? Ok, go to Wiki and read:
Public offer
Addressed to an indefinite circle of persons and containing all the essential terms of the contract, a proposal from which the will of the offeror is seen to conclude an agreement on the conditions specified in the proposal with anyone who responds. A person who has performed the necessary actions in order to accept a public offer (for example, who has sent an application for the relevant goods) has the right to demand that the offeror fulfill contractual obligations.
I hope you get the gist and the highlighted words.

Answer 2

The information is open, so there can be no claims.
Especially given the fact that the source is indicated.

Answer 3

Yes, this is also called advertising, so, as an option, you can earn money :))))