Top Useful Web APIs

1.Web Audio API - This web audio API allows you to manipulate an audio stream, on the web.It can be used to add effects and filters to an audio source on the web. 

2.FullScreen API - This API enables fullscreen mode in web apps.It lets you select the element you want to view in fullscreen mode.In android phones, it will remove the browser's window and the Android top status bar(where the network status,battery status, etc. are displayed. 

3.Web Speech API - This API provides us with the capabilites to add speech synthesis and speech recognation to our web app.With this API we will be abl do on Android via its google speech or windows using cortana. 

4.Bluetooth API - This API lets us the bluetooth low energy device on our phone and use it to share data from a webpage another device.Imagine being able to create a web chat app that can send and receive messages from other phones via bluetooth. 

5.Channel Messaging API - This API allows two scripts in different browser contexts to communicate and pass messages to each other in a two way channel.The different browser contexts can be two scripts running in different tabs,two iframes in a script, the document and an iframe in a script,etc.