A simple web server that allows you to specify a JSON file based on a URL param.

simple-server.js

//https://nodejs.org/en/docs/guides/anatomy-of-an-http-transaction/
var myPort = 8080;//Set pot to one not used on your box

var fs = require('fs')
var http = require('http');
console.log('Starting server...')
var server = http.createServer(function(req, resp){
    console.log('Request received. ');

    //get url param and change file based on param or url
    var param = req.url.split('?');
    if (param.length > 1) {
        param = param[1].split('=');
        if (param.length > 1) {
            param = param[1];
        }
    }

    var fileLoc = '';//Map your params to files here
    switch(param){
        case 'bar':
        fileLoc = 'C:/Projects/nodebin/bar.json';
        break;
        case 'baz':
        fileLoc = 'C:/Projects/nodebin/baz.json';
        break;
        default:
        fileLoc = 'C:/Projects/nodebin/foo.json';
        break;
    }

    fs.readFile(fileLoc, 'utf8', function(err, data) {
        if (err) {
            consoole.log(err);
        }
        else {
            console.log(data);
            resp.statusCode = 200;
            resp.setHeader('Content-Type', 'application/json');

            resp.write(data);//Echo JSON
            resp.end();
        }
    });
}).listen(myPort);