Goto GoDoc is a browser extension for the Chrome web browser that lets you view the documentation of the current package on the website you're on.

The best way to get the most out of this tool is to install it on a package you use regularly. You can then click on the Goto GoDoc button and view the documentation of the current package. The extension will work for all the currently opened packages in your browser, but you need to have the Go tool installed on your system.

Apart from that, Goto GoDoc also lets you search for all the packages that provide a public source code repository.