Open Contacts is the portable version of Open Contacts which is an address book program (contact and relationship management) providing unified, flexible and intuitive interfaces for you to manage and lookup contact info of individuals and organizations.

It has unlimited data fields to store any contact info and along with predefined fields, you may add unlimited data fields grouped by section. You can manage relationships between individuals, organizations and departments. It also has comprehensive categories - right click to list contacts of subcategories recursively.

You can search through any data field, and search birthdays as well as interact with telephony apps such as, Skype, emailing or Web/File browsing etc.