Is there an online application that can be used to test out an API?
I am interested in one that supports a REST API with basic authentication. I know there is a Firefox plugin that I could use for this, but was wondering if there is a web app.
If it's an OData endpoint, you can use the excellent OData Explorer:
Or the latest version of LinqPad which supports OData data sources:
For "generic" HTTP/REST services, you can use Fiddler to capture requests and replay them later:
Give this a try
They support Twitter , SimpleGeo and other popular Web Services API for testing.