A method, system, and computer program product for operating a web browser in an open browsing mode and a private browsing mode. The method may include calculating, by a computer processor, a privacy probability that a website contains information sensitive to the user. The privacy probability may be based, at least in part, on historical use of the private browsing mode by the user. The method may also include comparing the privacy probability to a privacy threshold and automatically switching the browser from the open browsing mode to the private browsing mode for the website if the privacy probability is greater than the privacy threshold.