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Where to find API documentation [0.5d]

There is no single place to look up documentation for our stack.

This card includes some hints where you can find API documentation. You probably want to drag a few of those links to your bookmarks toolbar. This will help in the upcoming exercises.


Basic classes like String, Error, Hash or Object are part of the Ruby standard library:

Ruby on Rails

Since you will use Rails more than any other gem, you will always want its documentation to be close:


ActiveSupport extends core classes in Ruby Archive .

We are so used to having ActiveSupport around that we don’t even think of it separate from Ruby anymore.
Which is why some methods you would expected to be documented in Ruby are actually in the Rails docs, e.g.


The best way to learn about a Ruby gem, Javascript libary, etc. is often to find the repository on Github and look at its README file. Here are a few examples:

Some libraries also publish dedicated sites with their documentation, e.g.:

Web Platform (HTML, JavaScript, CSS)

The best reference to look up information on HTML tags, JavaScript features or CSS properties is the English MDN Web Docs Archive .


The German version of MDN is full of incomplete and outdated articles. Only the English version of MDN is actively maintained.

Googling web terms will often rank German MDN articles very high. When you reach a German MDN article that way, the first thing you do is switch to the English version (link on the top right).

External APIs

When you're using external SaaS APIs, they often publish language-independent documentation. Some examples:

Anything not mentioned here

Google is your friend.

Henning Koch
Last edit
Almost 3 years ago
About this deck
We are makandra and do test-driven, agile Ruby on Rails software development.
Posted by Henning Koch to makandra Curriculum (2015-08-14 18:06)