I've stumbled upon a nice website which provides a tool for offline docs, It's called Zeal:
https://zealdocs.org
It contains 195 documentations of various languages and frameworks.
I'm sure some of you would find it very useful like I did.
[quote:g6mdwa86]AWS JavaScript ActionScript Akka Android Angular.dart AngularJS Ansible Apache HTTP Server Appcelerator Titanium AppleScript Arduino BackboneJS Bash Boost Bootstrap 2 Bootstrap 3 Bootstrap 4 Bourbon C C++ CMake CSS CakePHP Cappuccino Chai Chef Clojure Cocos2D Cocos2D-X Cocos3D CodeIgniter CoffeeScript ColdFusion Common Lisp Compass Cordova Corona CouchDB Craft D3JS Dart Django Docker Doctrine Dojo Drupal 7 Drupal 8 ElasticSearch Elixir Emacs Lisp EmberJS Emmet Erlang Express ExpressionEngine ExtJS Flask Font Awesome Foundation GLib Go Gradle DSL Gradle Groovy API Gradle Java API Gradle User Guide Grails Groovy Groovy JDK Grunt Gulp HTML Haml Handlebars Haskell Ionic Jade Jasmine Java EE6 Java EE7 Java SE6 Java SE7 Java SE8 JavaFX JavaScript Jekyll Jinja Joomla Julia KnockoutJS Kobold2D LaTeX Laravel Less Lo-Dash Lua 5.1 Lua 5.2 Lua 5.3 MarionetteJS Markdown Meteor Mocha MomentJS MongoDB Mongoose Mono MooTools MySQL NET Framework Neat Nginx NodeJS NumPy OCaml OpenCV C OpenCV C++ OpenCV Java OpenCV Python OpenGL 2 OpenGL 3 OpenGL 4 PHP PHPUnit Pandas Perl Phalcon PhoneGap Play Java Play Scala Polymer.dart PostgreSQL Processing PrototypeJS Puppet Python 2 Python 3 Qt 4 Qt 5 R Racket React Redis RequireJS Ruby Ruby 2 Ruby on Rails 3 Ruby on Rails 4 Ruby on Rails 5 RubyMotion Rust SQLAlchemy SQLite SVG SailsJS SaltStack Sass Scala SciPy Semantic UI Sencha Touch Sinon Smarty Sparrow Spring Framework Statamic Stylus Susy Swift Symfony TYPO3 Tcl Tornado Twig Twisted TypeScript UnderscoreJS Unity 3D VMware vSphere Vagrant Vim VueJS WordPress XSLT XUL Xamarin Xojo YUI Yii Zend Framework 1 Zend Framework 2 Zend Framework 3 ZeptoJS jQuery jQuery Mobile jQuery UI matplotlib