It is a extension (add-on) for Chrome and Firefox. It is used to quick open standard URL where one parameter is changed (Jira, other issue trackers, Youtube). For example, to quick open https://issues.apache.org/jira/browse/IO-279 it need enter only parameter 279.
You can add many different URLs.
For Firefox see Firefox Add-ons
For Chrome see Chrome Webstore
Or download files from Releases page.