Most sites like twitter,facebook, have exposed their API as RESTful webservices. [tpb]What do you need to access these APIs ?[/tpb] A Http library like http://hc.apache.org/ And a parsing library depending upon the type of response (JSON / XML ) I liked http://jackson.codehaus.org/ for its "Simple Data Binding" explained here http://wiki.fasterxml.com/JacksonInFiveMinutes [tpb]Can I send requests right away using a http library ?[/tpb] It depends ! Some requests need to be authorized. Imagine unauthourized access to "POST" messages ! [tpb]How can I send authorized requests ?[/tpb] The user first authorizes your app do some tasks. (like fetch some info / post some info ) User authorizing, (in terms of code) simply means that you are provided "tokens" Then when you send a request, you'd sign the request with these tokens. [tpb]What do I need to sign requests[/tpb] A library like SignPost