Cheat.sh

cheat.sh allows you to access public cheat sheets and howtos on an unified resource.

Compared to official man pages, it supplies more practical information.

You may try the application just with cURL:

$ curl cheat.sh

A couple of example queries:

$ curl curl cht.sh/php/sort
$ curl cht.sh/go/reverse+a+list
$ curl cht.sh/tar

At the moment, 55 programming languages are covered. They merge Stackoverflow and public cheat sheet repositories.

It also has a cht.sh command line tool which is more convenient to use compared to good, old cURL.
cht.sh comes with tab completion support, shell mode, clipboard integration, query history support.

It's an open-source project and distributed under MIT license.