Type Array
Mandatory No
"protocol_handlers": [
    "protocol": "ircs",
    "name": "IRC Mozilla Extension",
    "uriTemplate": "https://irccloud.mozilla.com/#!/%s"

Use this key to register one or more web-based protocol handlers.

A protocol handler is an application that knows how to handle particular types of links: for example, a mail client is a protocol handler for "mailto:" links. When the user clicks a "mailto:" link, the browser opens the application selected as the handler for the "mailto:" protocol (or offers them a choice of handlers, depending on their settings).

With this key, you can register a website as a handler for a particular protocol. The syntax and semantics of this key is very much like the Navigator.registerProtocolHandler() function, except that with registerProtocolHandler() a website can only register itself as a handler.

Each protocol handler has three properties, all mandatory:


A string defining the protocol. This must be either:

  • one of the following: "bitcoin", "geo", "gopher", "im", "irc", "ircs", "magnet", "mailto", "mms", "news", "nntp", "sip", "sms", "smsto", "ssh", "tel", "urn", "webcal", "wtai", "xmpp".
  • a string consisting of a custom name prefixed with "web+" or "ext+". For example: "web+foo" or "ext+foo". The custom name must consist only of lower-case ASCII characters. It's recommended that extensions use the "ext+" form.
A string representing the name of the protocol handler. This will be displayed to the user when they are being asked if they want this handler to open the link.
A string representing the URL of the handler. This string must include "%s" as a placeholder: this will be replaced with the escaped URL of the document to be handled. This URL might be a true URL, or it could be a phone number, email address, or so forth. This is a localizable property.


"protocol_handlers": [
    "protocol": "magnet",
    "name": "Magnet Extension",
    "uriTemplate": "https://example.com/#!/%s"

Browser compatibility

ChromeEdgeFirefoxFirefox for AndroidOpera
Basic supportNoNo5454No

Document Tags and Contributors

 Contributors to this page: wbamberg, K3N, andrewtruongmoz, SamBull
 Last updated by: wbamberg,