A system for automatically completing fields in online forms, such as login forms and new user registration forms, which employs a Master Cookie File containing sets of records associated with the user, his or her accounts or web sites, and registered values associated with form tags (e.g. username, password, address, email, telephone, etc.). When the user encounters another form, the MCF is automatically searched for matching values and form tags, primarily from the same account or web site, or alternatively from other accounts or sites. A flowing pop-up menu is displayed nearby the form fields from which the user can select values to automatically complete the form. Automatic account information updating, value expiration management, mapping of favorite values, and sharing of values are optional, enhanced functions of the invention.