Fast changing data feed for software demonstration (data)

Question

I'm looking for a

1. Fast changing
2. Easy-to-deserialize (xml or json)
3. Well formatted
4. Free

data feed (I was thinking about a REST API, but I welcome any suggestion) for demonstrating a Java software component.

I don't really care what the data is about (weather, finance, anything goes), the main criteria is, that it should change pretty fast (new stuff at least every 5-10 seconds), and the format of the data should be well defined, so a JAXB / Gson parser can handle it.

If you have ever used such an open API, then please let me know!

Answer 1

Well, if you will accept that it returns a different, random, value every item you ask, then a "fast changing source" would be the one that I accepted to my question JSON test server with regularly updating data.

To quote the accepted answer:

NumbersAPI will return at least dozens of distinct JSON formatted responses for requests to this URI endpoint. No registration required.

http://numbersapi.com/random/date?json

The date option returns something like this:

{
 "text": "May 26th is the day in 1830 that the Indian Removal Act is passed by the U.S. Congress; it is signed into law by President Andrew Jackson two days later.",
 "year": 1830,
 "number": 147,
 "found": true,
 "type": "date"
}

There are other types of data available.

If you read my question, you will see another proposed answer involving GitHub user data, which I imagine changes quickly, as new users sign up. I am not sure if it is quick enough, though.

Personally, I was more than happy with NumbersAPI for testing porpoises.

Answer 2

Although my previous answer was accepted, I have now found something which I consider to be far superior.

Mockaroo lets you generate up to 1,000 rows of realistic test data in CSV, JSON, SQL, and Excel formats. It has 89 predefined data types, plus conditional logic.

Check it out!