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Type Array
Mandatory No
"protocol_handlers": [
    "protocol": "ircs",
    "name": "IRC Mozilla Extension",
    "uriTemplate": "!/%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", "dat", "dweb", "geo", "gopher", "im", "ipfs", "ipns", "irc", "ircs", "magnet", "mailto", "mms", "news", "nntp", "sip", "sms", "smsto", "ssb", "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": "!/%s"

Browser compatibility

ChromeEdgeFirefoxFirefox for AndroidOpera
Basic support No No5454 No
dat No No5959 No
dweb No No5959 No
gopher No No5656 No
ipfs No No5959 No
ipns No No5959 No
ssb No No5959 No

Document Tags and Contributors

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