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# LUD-15: `balanceNotify`: services hurrying up the withdraw process.

> Display inline code and code blocks

`author: fiatjaf` `author: lafaire` `discussion: https://t.me/lnurl/9729`

***

## `balanceNotify`

This optional property works together with `balanceCheck` to make it instant. It works as follows:

* If `LN SERVICE` supports `balanceCheck`, then `LN WALLET` may decide to send an query-string-encoded HTTP URL along with the payment request when first making a withdrawal.
* `LN SERVICE` may store that URL and make a blank `HTTP POST` call to it the next time the given user has a balance in its account on the service.
* Upon receiving that `HTTP POST`, the wallet may decide to perform a balance check and withdraw the funds immediately.
* The scheme works for custodial wallets, Lightning nodes that have a domain name and an always-online online presence, and also for noncustodial mobile wallets that have a friendly server online that is able to receive that `HTTP POST` and notify them somehow.

The callback URL sent by the `WALLET` is modified as follows:

```diff theme={null}
-<callback><?|&>k1=<k1>&pr=<lightning invoice>
+<callback><?|&>k1=<k1>&pr=<lightning invoice>&balanceNotify=<URL>
```