Zeal allows you to consult easily and quickly the documentation of different programming languages.

Programming languages consist of multiples functions, classes, expressions, etc, this is known as the API (Application Programming Interface). A programmer must know well the programming language's API. To do this, you can query the programming language Online documentation. This involves a series of drawbacks, such as being limited by the online search engine of the API, or depend on the connection to the Internet to browse the programming language API.

Zeal arises as a solution that allows us to query in an organized and systematic way the APIs of different programming languages.
In this application we will be able to download the APIs documentation from a multitude of programming languages, such as: PHP, Javascript, Java, Python, Ruby, Scala, Swift, C/C++, ASP, Clojure, Go, Perl, etc.
in Addition we will also be able to download the APIs from different frameworks, including: Django, Symfony, Laravel, Ruby on Rails, Yii, etc.
We also can access other APIs as: HTML, CSS, Joomla, Drupal, Emmet, OpenCV, PhoneGap, MySQL, Unity 3D, etc.

We must download the APIs documentation to be able to make use of them. This is a great advantage, because once downloaded to our computer, there is no need to be connected to the Internet to query the documentation.
To download the APIs documentation you must follow these steps: Edit->Options->Docsets. In the bottom you will see a list with all the available APIs ready to be downloaded. We will select those docs that we're interested in, and click on the “Download” button.

Once we have downloaded the documents from the APIs we are interested in, we will see all the downloaded APIs on the left side of the main screen.
We will be able to navigate through the APIs as if they were directories, in such a way that we will be able to see a list with all the modules, methods, classes, exceptions, etc. of the APIs.
If you select any of the documents on the left column, you will see the information of this document on the right column. This document is like a web page and we will be able to click on the links to continue reading information related to this document. Pressing Ctrl+F, we will be able to search for any word within the selected document.
The program comes with a global search engine located at the top left column. This search engine make a search on all the downloaded APIs.
If we want to perform a search in a single document, we must enter the name of the programming language plus a colon, followed by the word we want to search. For example, if we want to search information about the javascript function “map”, we must enter the following on the search box: javascript:map

To launch the program, we can configure a keyboard shortcut (Alt+space bar), in such a way that the program is always at hand, and we can query the APIs quickly.

Despite the fact that the program is very useful and comfortable due to the combination of keys, we can make the most of it functionality and integrating it with our favorites editors as Sublime Text, Emacs, Vim, Brackets or IntelliJ IDEA.
For example if we install the Sublime Text plugin that allows to integrate Zeal, we can press the Shift+F1 key combination and use the Sublime Text search box to search on the downloaded APIs documentation.
we Also have the ability to select a word on the code that we are writing, and pressing the F1 key Zeal will be launched, and will show the related to documentation. For example if we are editing a HTML document and we select the word “href”, and press F1, we will see the information related to that HTML attribute.

This program is free and is available for Windows and Linux.