google finance

There aren’t really much APIs for stocks out there, fortunately, Google provides you a free, yet powerful API to access the stock data that used in Google Finance. (Update once every 5 min, and up to 20 min of delay.)

With the help of a feature (new trick, Google called it) that Google added to the Spreadsheets late last year, GoogleFinance, and with the Spreadsheets API, we can obtain the data easily in XML and JSON format. Demo using the JSON format can be found here. (GOOG data are used in the examples)

I will probably writing some tutorials, perhaps doing a screen cast on how to use this in the real world. (such as on a web page) :) But until then, you should take a look at the Spreadsheet Data API Reference Guide, and the help page for GoogleFinance function in the Spreadsheets. (if you are interested in using this API)

note: this is not really an official API that Google provides.