Inspection & Tweak FirefoxFirefox Developers Conference 2015 in Tokyo

http://www.freeimages.com/photo/true-love-searching-1579146

HTML + CSS + JavaScript

https://www.flickr.com/photos/artibite/16737362847

Web Audio API

var context = new AudioContext();

var audio = document.querySelector("audio");

var source = context.createMediaElementSource(audio);

var filter = context.createBiquadFilter();

source.connect(filter);

filter.connect(context.destination);

Network

Inspection & Tweak of DOM

Canvas Editor

Style Editor

Animation Tools

Storage

http://devtoolschallenger.com/

Inspection (& Tweak) JavaScript codes

Debugger

Performance

Memory

https://hacks.mozilla.org/category/developer-tools/