Navigator.registerProtocolHandler()

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

The Navigator method registerProtocolHandler() lets websites register their ability to open or handle particular URL schemes (aka protocols).

For example, this API lets webmail sites open mailto: URLs, or VoIP sites open tel: URLs.

Syntax

navigator.registerProtocolHandler(scheme, url);

Note: The original implementation required three arguments: navigator.registerProtocolHandler(scheme, url, title), which most browsers still support (see the compatibility table below). It is recommended to still set the title, since browsers that support the updated spec will most likely be backwards-compatible and still accept the title (but not use it).

Parameters

scheme: A string containing the protocol the site wishes to handle. For example, you can register to handle SMS text message links by passing the "sms" scheme.
url: A string containing the URL of the handler. %s, as a placeholder that will be replaced with the escaped URL to be handled.

Note: The handler URL must use the https scheme. Older browsers also supported http.
title: A human-readable title string for the handler. This will be displayed to the user, such as prompting “Allow this site to handle [scheme] links?” or listing registered handlers in the browser’s settings.

Note: The title has been removed from the spec due to spoofing concerns, but some browsers still require it (check the compatibility table below). It is recommended to always set the title, since browsers that support the updated spec most likely will be backwards-compatible and still accept the title (but not use it).

Exceptions

SecurityError: The user agent blocked the registration. This might happen if:

The registered scheme (protocol) is invalid, such as a scheme the browser handles itself (https:, about:, etc.)
The handler URL’s origin does not match the origin of the page calling this API.
The browser requires that this function is called from a secure context.
The browser requires that the handler's URL be over HTTPS.

SyntaxError: The %s placeholder is missing from the handler URL.

Permitted schemes

For security reasons, registerProtocolHandler() restricts which schemes can be registered.

A custom scheme may be registered as long as:

The custom scheme's name begins with web+
The custom scheme's name includes at least 1 letter after the web+ prefix
The custom scheme has only lowercase ASCII letters in its name.

For example, web+burger, as shown in the Example below.

Otherwise, the scheme must be one of the following:

bitcoin
geo
im
irc
ircs
magnet
mailto
matrix
mms
news
nntp
openpgp4fpr
sip
sms
smsto
ssh
tel
urn
webcal
wtai
xmpp

Example

If your site is burgers.example.com, you can register a protocol handler for it to handle web+burger: links, like so:

navigator.registerProtocolHandler("web+burger",
                                  "https://burgers.example.com/?burger=%s",
                                  "Burger handler"); // last title arg included for compatibility

This creates a handler that lets web+burger: links send the user to your site, inserting the accessed burger URL into the %s placeholder.

This script must be run from the same origin as the handler URL (so any page at https://burgers.example.com), and the handler URL must be http or https.

The user will be notified that your code asked to register the protocol handler, so that they can decide whether or not to allow it. See the screenshot below for an example on google.co.uk:

A browser notification reads “Add Burger handler (www.google.co.uk) as an application for burger links?”, and offers an “Add Application” button and a close to ignore the handler request.

Specifications

Specification
HTML Standard (HTML) # custom-handlers

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`registerProtocolHandler`	13 ["Allowed schemes include `mailto`, `mms`, `nntp`, `rtsp`, and `webcal`. Custom protocols must be prefixed with `web+`.", "From Chrome 77, the URL parameter only accepts `http` or `https` URLs.", "The obsolete `title` argument is required."]	79 ["Allowed schemes include `mailto`, `mms`, `nntp`, `rtsp`, and `webcal`. Custom protocols must be prefixed with `web+`.", "The obsolete `title` argument is required."]	3	No	11.6 The obsolete `title` argument is required.	No	No	No	No	No	No	No
`secure_context_required`	80	79	62	No	67	No	No	No	No	No	No	No