LNURL is a bech32-encoded HTTPS/Onion query string which is supposed to help payer interact with payee and thus simplify a number of standard scenarios such as:
- Requesting incoming channels (LNURL-channel)
- Logging in (LNURL-auth)
- Withdrawing funds (LNURL-withdraw)
- Paying for a service (LNURL-pay)
An example LNURL:
https://service.com/api?q=3fc3645b439ce8e7f2553a69e5267081d96dcd340693afabe04be7b0ccd178df
would be bech32-encoded as:
LNURL1DP68GURN8GHJ7UM9WFMXJCM99E3K7MF0V9CXJ0M385EKVCENXC6R2C35XVUKXEFCV5MKVV34X5EKZD3EV56NYD3HXQURZEPEXEJXXEPNXSCRVWFNV9NXZCN9XQ6XYEFHVGCXXCMYXYMNSERXFQ5FNS
and presented as the following QR:
Once LNURL is decoded:
- If
tagquery parameter is present then thisLNURLhas a special meaning, further actions will be based ontagparameter value. - Otherwise a GET request should be executed which must return a Json object containing a
tagfield, further actions will be based ontagfield value.
LNURL is acceptable in two forms: either an https:// clearnet link (no self-signed certificates allowed) or an http:// v2/v3 onion link.
LNURL can be used as fallback inside of other URI schemes, with the key 'lightning' and the value equal to the bech32-encoding, an example: https://service.com/giftcard/redeem?id=123&lightning=LNURL1...
In Scala:
import fr.acinq.bitcoin.Bech32
val bech32lnurl: String = "LNURL1DP68GURN8GHJ7UM9WFMXJCM99E3K7MF0V9CXJ0M385EKVCENXC6R2C35XVUKXEFCV5MKVV34X5EKZD3EV56NYD3HXQURZEPEXEJXXEPNXSCRVWFNV9NXZCN9XQ6XYEFHVGCXXCMYXYMNSERXFQ5FNS"
val (hrp, dataPart) = Bech32.decode(bech32lnurl)
val requestByteArray = Bech32.five2eight(dataPart)
new String(requestByteArray, "UTF-8") // https://service.com/api?q=3fc3645b439ce8e7f2553a69e5267081d96dcd340693afabe04be7b0ccd178dfIf you have any questions about implementing LNURL as a wallet or service, join us in the BLW Telegram and get help from the creators and other LNURL implementors.