This is a simple web app using node express and mongodb with restful apis
What this web-app do:
Store and retrive JSON data in a mongoDB collection using HTTP POST and HTTP GET
Used ajax for data operations and update page with jQuery.
Let see how to set this app.
1.install node.js can be downloaded from  http://nodejs.org/
2.install express- open node.js commonad prompt and type npm install -g express
Download Mongodb from here http://www.mongodb.org/downloads and download your release as per your requirement. 
Copy and extract this application some where in your pc.
now open system commond prompt
go to path where mongodb is installed like for me it is:
C:\Program Files\MongoDB 2.6 Standard\bin
so in cmd prompt type below commands 
1.cd C:\Program Files\MongoDB 2.6 Standard\bin
2.mongod --dbpath [path to 'userdata' folder in web-app eg. C:\Users\nitin.g6\Desktop\simpleapp\userdata] 
open a new command prompt and type below commands
1.cd C:\Program Files\MongoDB 2.6 Standard\bin
2.mongo
Now the db is up and running, type below command to start the application
npm install

application is running now which you can access from localhost:3000 in your browser