A system and application for purchasing one or more items via quick online transactions from a vendor system is provided. An electronic shopping page listing products for sale and corresponding buy selectors is provided on a user device that includes the quick transaction system. Upon user selection of a buy selector, the user's log on status and payment information are determined, and, if necessary, the user is prompted to log on to the quick transaction application and/or complete any missing user payment information if necessary. A single click or tap on the buy selector generates a completed purchase transaction without the need for a shopping cart or user checkout process. Methods and machine-readable medium for quick online transactions are also provided.