Operator was an extension for the Mozilla Firefox web browser.

[1][2] It parses[2] and acts upon a number of microformats,[1][2][3] as well as validating them.

[2] Operator lets the user access microformats through a number of methods, all of which are optional: a toolbar, a toolbar button, a status bar icon, a location bar icon, or a sidebar.

Operator was written by Mike Kaply of IBM.

[6] It forms the basis for Firefox 3's microformats API,[5][7] allowing native support, but has no direct user interface, due to lack of consensus on the implementation in the GUI.