What tools can I use to test Web services and APIs? what is the best tool for API testing

There are number of tools available in the market.
We can do web service testing by using either
Soap Ui,
Jmeter
or by using programming  we can write either in JAVA, Python, Ruby.

If you would like to go by programming.I would say that also depends on your development team what programming language web services are written. You might want to use the same programming language in order to have developers support.

For API testing you don't need to deal with browser related and UI/ elements related hassle.

Testing WebServices is much easier than testing GUI. In nut-shall, you need to understand how HTTP requests are made & how responses can be consumed? Requests and responses are usually in the form of JSON or XML so you need to know relevant libraries (depending on the language you are using).

JMeter is also a good choice given that it's open source/free, it's relatively easy to use, and because it gives you rudimentary performance data with your test runs (average, min, max, median response times for all requests).

If you're open to a programming approach to testing, There is a tool called REST Assured over JMeter or similar tool. http://code.google.com/p/rest-assured/ A combination of TestNG and RESTAssured makes things pretty simple.



http://www.testinggeek.com/testing-restful-webservices-or-api-testing-remember-papas-be-sfo-deed-help-gc-and-dvla-pc#!