Zuora, one of the startups that provides on-demand software to manage companies’ billing and payments, aims to take advantage of growing interest in cloud computing with a new product dubbed Z-Commerce, which will provide Zuora’s services to developers on cloud platforms like Amazon Web Services and Google App Engine.

The Redwood City, Calif. startup has already released three products: Z-Billing, which automates the billing process; Z-Payments, which integrates with PayPal to handle the actual payments; and Z-Force (perhaps the only Zuora application whose name isn’t completely self-explanatory), a billing and payment system that integrates with Salesforce.com. What Z-Commerce adds to the mix is as much about audience as it is about functionality - where the other applications targeted a company’s finance department, Z-Commerce is meant for developers to use directly.