It's "freemium", not free. There is a difference. You can't use ChatGPT 4 without paying as well as the API. Also, you are limited in the number of prompts you can make per hour before you are put on pause and asked to pay.
Search engines like Ecosia, DuckDuckGo, etc. don't ask you for money. Regardless how intensively you use it. (They might come with other drawbacks though like Google with privacy, environment, ethical principles, ...)