JSON validator, schema generator and JSON url automation testing API?

I'm new to testing tools and android testing (I have theoretical background of testing). I want to test JSON data against its schema with a tool. I know there are some online tools but I need a tool with an automation option to do this validation. And also I need a tool which does this: There will be a json service url like this: http://...requestId=3&channelId=3&nMSISDN=5304027851&nOperatorID=1... and I want to test what will happen if I change channelId=3 to channelId=5 or same thing to other parts of the url like "requestId=3 to requestId=4". I need to do this with a tool. Actually, I want to test web service's security with a tool. In short I need a JSON schema validator/generator and security API