Many online casinos offer no deposit bonuses to US players. If the online casino accepts players from the United States, then US players will be able to take advantage of any no deposit bonuses that they offer. If you are from the US, then you need to check to see if the casino accepts US players, because their are casinos that do not accept US players, and others that only accept players from certain US states.
Online casinos that use the RTG casino software typically accept US players, and most of the online casinos that cator to US players are offering no deposit bonuses. In most cases, US players will need to manually enter a bonus code within the cashier section of the online casinos to receive a no deposit bonus. This is typical for casinos that use the RTG casino platform, and most US-friendly casinos use this.