The RTCIceCandidate interface—part of the WebRTC API—represents a candidate Internet Connectivity Establishment (ICE) configuration which may be used to establish an RTCPeerConnection.

An ICE candidate describes the protocols and routing needed for WebRTC to be able to communicate with a remote device. When starting a WebRTC peer connection, typically a number of candidates are proposed by each end of the connection, until they mutually agree upon one which describes the connection they decide will be best. WebRTC then uses that candidate's details to initiate the connection.

For details on how the ICE process works, see Lifetime of a WebRTC session. The article WebRTC connectivity provides additional useful details.


Creates an RTCIceCandidate object to represent a single ICE candidate, optionally configured based on an object based on the RTCIceCandidateInit dictionary.
Note: For backward compatibility, the constructor also accepts as input a string containing the value of the candidate property instead of a RTCIceCandidateInit object, since the candidate includes all of the information that RTCIceCandidateInit does and more.


candidate Read only
A DOMString representing the transport address for the candidate that can be used for connectivity checks. The format of this address is a candidate-attribute as defined in RFC 5245. This string is empty ("") if the RTCIceCandidate is an "end of candidates" indicator.
component Read only
A DOMString which indicates whether the candidate is an RTP or an RTCP candidate; its value is either "rtp" or "rtcp", and is derived from the "component-id" field in the candidate a-line string. The permitted values are listed in the RTCIceComponent enumerated type.
foundation Read only
Returns a DOMString containing a unique identifier that is the same for any candidates of the same type, share the same base (the address from which the ICE agent sent the candidate), and come from the same STUN server. This is used to help optimize ICE performance while prioritizing and correlating candidates that appear on multiple RTCIceTransport objects.
ip Read only
A DOMString containing the IP address of the candidate.
port Read only
An integer value indicating the candidate's port number.
priority Read only
A long integer value indicating the candidate's priority.
protocol Read only
A string indicating whether the candidate's protocol is "tcp" or "udp". The string is one of those in the enumerated type RTCIceProtocol.
relatedAddress Read only
If the candidate is derived from another candidate, relatedAddress is a DOMString containing that host candidate's IP address. For host candidates, this value is null.
relatedPort Read only
For a candidate that is derived from another, such as a relay or reflexive candidate, the relatedPort is a number indicating the port number of the candidate from which this candidate is derived. For host candidates, the relatedPort property is null.
sdpMid Read only
A DOMString specifying the candidate's media stream identification tag which uniquely identifies the media stream within the component with which the candidate is associated, or null if no such association exists.
sdpMLineIndex Read only
If not null, sdpMLineIndex indicates the zero-based index number of the media description (as defined in RFC 4566) in the SDP with which the candidate is associated.
tcpType Read only
If protocol is "tcp", tcpType represents the type of TCP candidate. Otherwise, tcpType is null.
type Read only
A DOMString indicating the type of candidate as one of the strings from the RTCIceCandidateType enumerated type.
usernameFragment Read only
A DOMString containing a randomly-generated username fragment ("ice-ufrag") which ICE uses for message integrity along with a randomly-generated password ("ice-pwd"). You can use this string to verify generations of ICE generation; each generation of the same ICE process will use the same usernameFragment, even across ICE restarts.


Given the RTCIceCandidate's current configuration, toJSON() returns a DOMString containing a JSON representation of that configuration in the form of a RTCIceCandidateInit object.


For examples, see the article Signaling and video calling, which demonstrates the entire process.


Specification Status Comment
WebRTC 1.0: Real-time Communication Between Browsers
The definition of 'RTCIceCandidate' in that specification.
Candidate Recommendation Initial definition.

Browser compatibilityUpdate compatibility data on GitHub

Chrome Edge Firefox Internet Explorer Opera Safari
Basic support Yes Yes 22 ? Yes ?
RTCIceCandidate() Yes Yes 22 ? Yes ?
candidate Yes 15 22 ? Yes ?
foundation No Yes No No No ?
ip No Yes No No No ?
port No Yes No No No ?
priority No Yes No No No ?
protocol No Yes No No No ?
relatedAddress No Yes No No No ?
relatedPort No Yes No No No ?
sdpMid Yes 15 22 ? Yes ?
sdpMLineIndex Yes 15 22 ? Yes ?
tcpType No Yes No No No ?
type No Yes No No No ?
component No ? No No ? ?
usernameFragment ? ? No ? ? ?
toJSON ? 15 27 ? ? ?
Android webview Chrome for Android Edge Mobile Firefox for Android Opera for Android iOS Safari Samsung Internet
Basic support Yes Yes Yes ? Yes ? Yes
RTCIceCandidate() Yes Yes Yes ? Yes ? Yes
candidate Yes Yes Yes ? Yes ? Yes
foundation No No Yes ? No ? Yes
ip No No Yes No No ? Yes
port No No Yes No No ? Yes
priority No No Yes No No ? Yes
protocol No No Yes No No ? Yes
relatedAddress No No Yes No No ? Yes
relatedPort No No Yes No No ? Yes
sdpMid Yes Yes Yes ? Yes ? Yes
sdpMLineIndex Yes Yes Yes ? Yes ? Yes
tcpType No No Yes No No ? Yes
type No No Yes No No ? Yes
component No No ? No ? ? ?
usernameFragment ? ? ? No ? ? ?
toJSON ? ? ? 27 ? ? ?

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