Shares of the cloud-based data storage company closed up over 35 percent after its first day of trading, at $28.48 a share, well above the company's stated price of $21.
"If you were paying attention over the course of the session, you know that this was a white-hot deal," the "Mad Money" host said. "This is exactly the kind of stock that Wall Street wants right now."
Cramer's main point of concern was whether Dropbox would be able to keep turning its non-paying subscribers into paying customers. To maintain its growth rate, it needs to switch between two million and four million free users into paying customers each year.
But that's less than 1 percent of its 500 million free subscribers, Cramer noted, adding that the company will now have millions of dollars to invest in and bolster the business.