> ## Documentation Index
> Fetch the complete documentation index at: https://docs-en.keysecure.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

`POST /user callback notification address`

#### Common Request Parameters

| Param | Type | Required | Description |
| :- | :- | :- | :- |
| app\_id | String | Yes | merchant unique identifier |
| data | String | Yes | encrypted String, decrypted format is defined as `Decrypted Request Parameters` |

#### Common Response

Return string （note that the return parameter does **not need to be encrypted** here）：

* `SUCCESS` means SUCCESS
* `FAILURE` means FAILURE


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