The service combines QAS's contact data management technology with Experian's secure hosting capabilities.
The launch marks 's entry into the software service market, which is expected to double to $12bn by 2012, according to industry analyst Gartner.
Pro On Demand allows users to enter partial address information, such as a postcode and premises number, and then instantly returns a complete and correctly formatted address, validated against the Royal Mail's Postcode Address File.
For website contact data management, the service claims to enable organisations to greatly reduce the costs associated with incomplete and duplicate registrations.
Pro On Demand has been designed to provide total contact data management flexibility for organisations of all sizes.
Experian claims that smaller companies will benefit from having data hosted and managed so that they can free up valuable internal IT resources, while larger companies can integrate the service into existing service-orientated architecture strategies.
Jonathan Hulford-Funnell, group operating officer at Experian QAS, said: "Software as a service is an efficient and simple way to maintain contact data.
"Feedback from clients already shows that the combination of QAS's and Experian's capabilities to create QAS Pro On Demand is a compelling proposition."