Among the 25 finance APIs now listed on ProgrammableWeb, there are services from old and new companies, and large and small companies. For example, the venerable Dun and Bradstreet offers the Dun and Bradstreet Credit Check API, personal finance startup Wesabe offers an API and there's an API from Prosper, a peer-to-peer lending service. Overall, most current business and finance APIs fall into one of two categories: APIs from SaaS-based business administration and management services, and APIs that provide financial markets data.

SaaS Business Administration APIs

A variety of new on-demand service providers offer APIs as a means to reach and integrate with their services. For example, the Blinksale API accesses their online invoicing service. The REST API provides access to your Blinksale data, letting you create invoices using a Blinksale invoice template or one of your own creation.

The FreshBooksTrack this API API provides online invoicing and time tracking using your Freshbooks account. The KashFlow and NetAccountsTrack this API APIs offer broader accounting capabilities, geared toward businesses in the UK and Australia, respectively.

Financial Data APIs

Looking for real-time financial market quotes or historical data? Fifteen APIs are ready to get you the data you need, when you need it. Xignite provides financial data APIs ranging from XigniteRealtimeTrack this API and XigniteFundsTrack this API (real-time U.S. stock market quotes, and U.S. mutual fund data) to XigniteCurrenciesTrack this API and XigniteRatesTrack this API (currency and international interest rate data) to XigniteEdgarTrack this API and XigniteCalendarTrack this API (U.S. SEC Edgar filings and global economic calendars). The Xignite APIs feature SOAP and REST protocols, with all data returned in XML format. Once you've used one Xignite API, it's relatively easy to get started with others, since all the APIs incorporate a common design structure.

StrikeIron offers a number of APIs that serve users with U.S. financial data including StrikeIron Stock Quotes BasicTrack this API, StrikeIron Mutual FundsTrack this API, and StrikeIron Historical Stock QuotesTrack this API. The StrikeIron APIs utilize SOAP protocol and return results in XML format.

Timepost Mashup

Business and Financial APIs provide excellent opportunities for developing mashups. One example is the Timepost mashup, which applies the Blinksale and FreshBooks business APIs, along with the popular Basecamp APITrack this API (from 37signals) and the HarvestTrack this API time-tracking API. Integration of these APIs results in a rich time tracking and project collaboration solution for small businesses.