The PayPal X platform was unveiled at the firm's inaugural developers conference in San Francisco after several months of testing with over a thousand outfits.

PayPal, facing increasing competition from the likes of Amazon and Google, is hoping to boost business by tapping the potential of third parties in the same way Facebook and Apple have.

Earlier this year, John Donahoe, president and CEO of parent company eBay, said he wants to double PayPal revenue within three years and claimed the unit has the potential to become bigger than eBay Marketplaces because it targets all of e-commerce.

The company hopes the PayPal X platform will let it reach new markets by embedding the system in a variety of sites that would not previously have used it.

Scott Thompson, president, PayPal, says: "The whole world is going digital, and the future of how we communicate, how we get information, and even how we transact, is in the hands of developers. The network is the platform on which the potential of digital money will be fully realized."

The Adaptive Payments APIs that have been beta tested, and are now available to all developers, allow straight payments from customers to the PayPal accounts of receivers such as owners of Web sites or widgets on social networking sites.

The API is gaining traction in the top-end computing market, with Sun promising to use the app in its online Java store and Microsoft onboarding it for use in its Azure cloud computing model.

In addition, developers can build applications for "parallel payments", enabling a sender to make a payment to multiple receivers, and "chained payments" that will enable a sender to make a single payment to a "primary receiver", who can then keep a part of it and send the rest to "secondary receivers".

The firm has also added new APIs for currency conversion and a "pay anyone" feature that lets financial and other institutions enable customers to send money when logged in to their bank accounts without needing a PayPal account. FIS has announced plans to embed the feature within its online bill payment application for banks. When a sender initiates a personal payment and selects the free electronic option, the receiver's email address is entered to complete payment. From there an email immediately notifies the receiver of the payment, which is delivered in real-time over PayPal's network.

Pre-approval enables developers to create reusable payments agreements between buyers and sellers. While payment approval happens online, the actual money movement can occur offline at different intervals, and through multiple devices that are not necessarily Internet-connected at the time.

Additionally, a beta Adaptive Accounts API lets developers create PayPal accounts for their customers from within their applications.

PayPal X will also have a mobile payment software development kit (SDK) from the first half of next year, initially supporting the iPhone.

Osama Bedier, VP, platform, PayPal, says: "Mobile transactions have been notoriously tough to monetize. With the new SDK, just tell us how much you want to get paid and what the payment is for, and the funds will be transferred in seconds, not days or weeks."

PayPal has teamed with S1 Corporation to deliver a mobile cash transfer system and signed Mercantile Bank of Michigan as the first financial customer for the new system, which is expected to go live early next year.

The company is also wooing developers who build applications in markets that are traditionally served by cash and cheques, such as rent, consulting businesses or payroll.

From Q2 2010, fees will be 50 cents or 0.75% of the value of the transaction based on the speed of settlement - lower than the firm's normal fees.

One firm to tap the PayPal X platform is start-up called Payvment, which has launched an e-commerce application for Facebook. Another outfit, PlaySpan has developed an in-app system to let users buy digital goods directly in online games. Another innovation comes from ShopSavvy, which will enable users of its mobile-based e-commerce price comparison service to make payments direct from the rankings without visiting the e-commerce store directly.