NWC Relay

Running or connecting to a relay

Relay servers route messages between client apps and wallets. NWC requires relay as an URL of the relay where the wallet service is connected and will be listening for events.

There are four event kinds:

• NIP-47 info event: 13194

• NIP-47 request: 23194

• NIP-47 response: 23195

• NIP-47 notification: 23197 (and 23196: legacy NIP-04 notifications)

The info event should be a replaceable event that is published by the wallet service on the relay to indicate which commands it supports. The content should be a plaintext string with the supported commands, space-separated, eg. pay_invoice get_balance.

Both the request and response events SHOULD contain one p tag, containing the public key of the wallet service if this is a request, and the public key of the user if this is a response. The response event SHOULD contain an e tag with the id of the request event it is responding to.

The content of requests and responses is encrypted with NIP04, and is a JSON-RPCish object with a semi-fixed structure:

Request:

{
    "method": "pay_invoice", // method, string
    "params": { // params, object
        "invoice": "lnbc50n1..." // command-related data
    }
}

Response:

{
    "result_type": "pay_invoice", //indicates the structure of the result field
    "error": { //object, non-null in case of error
        "code": "UNAUTHORIZED", //string error code, see below
        "message": "human readable error message"
    },
    "result": { // result, object. null in case of error.
        "preimage": "0123456789abcdef..." // command-related data
    }
}

The result_type field MUST contain the name of the method that this event is responding to. The error field MUST contain a message field with a human readable error message and a code field with the error code if the command was not successful. If the command was successful, the error field must be null.

Using a dedicated relay

NWC does not specify any requirements on the type of a Nostr-compatible relay. However, it makes sense to use a dedicated relay to prevent metadata leaks and improve reliability. Wallets can set up their own relay or leverage existing infrastructure listed here.