If you notice a small charge after signing up for a free plan that has potential overage costs, also known as "Freemium", it is likely a pre-authorization charge. But what does that mean?
Essentially, it is a temporary hold of a small amount of money placed by the merchant on your card to verify if there are sufficient funds available, and it lasts for a week. After this period, the hold is released and RapidAPI does not keep these funds.