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Documentation Index

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This endpoint implements the LNURL-pay well-known discovery step — the first step in the Lightning Address payment flow. When a wallet wants to pay username@domain.com, it fetches this URL to discover payment parameters and the callback URL it should use to request an invoice. All usernames resolve to the same underlying Buda.com account, so the username portion of the address is cosmetic and only affects the metadata description returned. 
GET /.well-known/lnurlp/:username

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Path parameters

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username
string
required
Any username string. All usernames resolve to the same Buda.com account regardless of what value is supplied here. This value is interpolated into the metadata description field as "Pago Lightning a {username}".

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Response (200 OK)

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callback
string
The URL wallets must call to request a Lightning invoice. Constructed dynamically from the DOMAIN environment variable (or the request’s Host header if DOMAIN is not set): {protocol}://{domain}/callback.
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maxSendable
integer
Maximum payable amount in millisatoshis: 100000000 (equivalent to 100,000 satoshis). Wallets will not offer amounts above this value.
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minSendable
integer
Minimum payable amount in millisatoshis: 1000 (equivalent to 1 satoshi). Wallets will not offer amounts below this value.
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metadata
string
A JSON-encoded array of metadata tuples as required by the LNURL-pay spec. Returns [["text/plain", "Pago Lightning a {username}"]] with the path :username interpolated.
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tag
string
Always "payRequest". Identifies this response as an LNURL-pay endpoint per the LUD-06 specification.
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commentAllowed
integer
Maximum number of characters allowed in the comment field when calling /callback. Set to 140 characters per LUD-09.
Amounts in this response — minSendable and maxSendable — are in millisatoshis, not satoshis. 1 satoshi = 1000 millisatoshis. When calling the /callback endpoint, pass the amount in millisatoshis as well.
The DOMAIN environment variable controls the hostname used to build the callback URL. If DOMAIN is not configured on the server, the callback is constructed from the incoming request’s Host header instead.

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Example

Request 
GET https://budaln.fly.dev/.well-known/lnurlp/nicolas
Response 
{
  "callback": "https://budaln.fly.dev/callback",
  "maxSendable": 100000000,
  "minSendable": 1000,
  "metadata": "[[\"text/plain\",\"Pago Lightning a nicolas\"]]",
  "tag": "payRequest",
  "commentAllowed": 140
}

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Spec compliance

This endpoint conforms to two LNURL specifications:
  • LNURL spec LUD-06 — Defines the payRequest tag and the base LNURL-pay flow: the wallet fetches this well-known URL, reads minSendable / maxSendable / callback, then calls the callback with a chosen amount to get a BOLT11 invoice.
  • LUD-09 — Extends LNURL-pay with an optional comment field. The commentAllowed: 140 field in the response signals that the /callback endpoint accepts a comment query parameter of up to 140 characters.

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