Support for extensions using XUL/XPCOM or the Add-on SDK was removed in Firefox 57, released November 2017. As there is no supported version of Firefox enabling these technologies, this page will be removed by December 2020.

Add-ons using the techniques described in this document are considered a legacy technology in Firefox. Don't use these techniques to develop new add-ons. Use WebExtensions instead. If you maintain an add-on which uses the techniques described here, consider migrating it to use WebExtensions.

Starting from Firefox 53, no new legacy add-ons will be accepted on (AMO) for desktop Firefox and Firefox for Android.

Starting from Firefox 57, only extensions developed using WebExtensions APIs will be supported on Desktop Firefox and Firefox for Android.

Even before Firefox 57, changes coming up in the Firefox platform will break many legacy extensions. These changes include multiprocess Firefox (e10s), sandboxing, and multiple content processes. Legacy extensions that are affected by these changes should migrate to use WebExtensions APIs if they can. See the "Compatibility Milestones" document for more information.

A wiki page containing resources, migration paths, office hours, and more, is available to help developers transition to the new technologies.



Interact with the system clipboard, setting and getting its contents.


You can optionally specify the type of the data to set and retrieve. The following types are supported:

  • text (plain text)
  • html (a string of HTML)
  • image (a base-64 encoded png)

If no data type is provided, then the module will detect it for you.

Currently the image type doesn't support transparency on Windows.


Set and get the contents of the clipboard.

var clipboard = require("sdk/clipboard");
clipboard.set("Lorem ipsum dolor sit amet");
var contents = clipboard.get();

Set the clipboard contents to some HTML.

var clipboard = require("sdk/clipboard");
clipboard.set("<blink>Lorem ipsum dolor sit amet</blink>", "html");

If the clipboard contains HTML content, open it in a new tab.

var clipboard = require("sdk/clipboard");
if (clipboard.currentFlavors.indexOf("html") != -1)
  require("sdk/tabs").open("data:text/html;charset=utf-8," + clipboard.get("html"));

Set the clipboard contents to an image.

var clipboard = require("sdk/clipboard");
clipboard.set("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAYA" +
              "AABzenr0AAAASUlEQVRYhe3O0QkAIAwD0eyqe3Q993AQ3cBSUKpygfsNTy" +
              "N5ugbQpK0BAADgP0BRDWXWlwEAAAAAgPsA3rzDaAAAAHgPcGrpgAnzQ2FG" +

If the clipboard contains an image, open it in a new tab.

var clipboard = require("sdk/clipboard");
if (clipboard.currentFlavors.indexOf("image") != -1)

As noted before, data type can be easily omitted for images. If the intention is set the clipboard to a data URL as string and not as image, it can be done by specifying a different flavor, like text.

var clipboard = require("sdk/clipboard");
clipboard.set("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAYA" +
              "AABzenr0AAAASUlEQVRYhe3O0QkAIAwD0eyqe3Q993AQ3cBSUKpygfsNTy" +
              "N5ugbQpK0BAADgP0BRDWXWlwEAAAAAgPsA3rzDaAAAAHgPcGrpgAnzQ2FG" +
              "bWRR9AAAAABJRU5ErkJggg%3D%3D", "text");



set(data, datatype)

Replace the contents of the user's clipboard with the provided data.


data : string
The data to put on the clipboard.

datatype : string
The type of the data, , one of "text", "html", "image". Optional.


Get the contents of the user's clipboard.


datatype : string
Retrieve the clipboard contents only if matching this type (optional). The function will return null if the contents of the clipboard do not match the supplied type.



Data on the clipboard is sometimes available in multiple types. For example, HTML data might be available as both a string of HTML (the html type) and a string of plain text (the text type). This property is an array contains all types in which the data currently on the clipboard is available.