How can you customize system URLs in OpenCart? For example, I would like http://example.com/index.php?route=checkout/cart to be displayed as http://example.com/cart
A simple "no code" method is to install vQmod. Instructions here: vQmod install wiki
And then upload the xml file available in this Opencart forum thread to the vqmod/xml/ folder.
The xml contains a relatively easy to read script that maps the urls similar to the two answers above, but without modifying core files. So site updates will not kill it.