Zeal Portable

Zeal Portable is a lightweight utility that enables you to access and download a plethora of API documentation sets, which you can access later on in offline mode.

Clean interface and straightforward functionality

The setup is as simple as it gets and entails decompressing the archive in the preferred location on your hard drive. Upon launch, you are welcomed by a modern and user-friendly interface that you can learn immediately. As you probably already hinted, first you need to get the API documentation you need so you can start browsing through it.
In spite of the fact that you do not need to be connected to the Internet to access your documentation in the long run, take note that you need to it to download the docsets you need. Once downloaded, they are stored in the same directory as the app and you can access them anytime without having to worry about your connection.

Allows you to download an extensive list of API documentation sets

As previously mentioned, you should download the necessary API before you can start taking advantage of the browser function. You can access the API from the Docsets function from the Tools menu. Once installed, you should be able to view the documentation available in the main window.
It is worth noting that the utility comes with a search function that permits you to look precise information, an option that can save you a lot of time and energy.
The highlight of the application comes from the impressive list of API documentation available, namely Dojo, Django, Font Awesome, Java, LaTeX, Mocha, NET Framework, OpenCV_C, PHP, Qt, Ruby, Rust, Sass, Tornado, so on and so forth.

A tool for anyone who needs to access API documentation offline

Irrespective of whether you are traveling frequently, but would still like to learn various APIs or maybe, you are working on an application already, Zeal Portable allows you to get the documentation you require and that you can access offline.