When integrating third-party messaging or SMS APIs, fetching your current unit balance programmatically helps monitor account limits and trigger automated low-balance alerts.

This guide demonstrates how to authenticate with a REST API using Bearer tokens and extract the unit balance payload using PHP cURL.

Endpoint Specifications

Endpoint URL: [https://api.example.com/v2/app/balance](https://api.example.com/v2/app/balance)

HTTP Method: POST

Authentication Header: Authorization: Bearer <YOUR_API_TOKEN>

Content-Type: application/json

Sample API Response Payload

The API returns account balance details in the following JSON structure:

JSON

{

"amount": "1000.00",

"userbalance": {

"amount": "1000.00",

"status": 1

},

"status": 1

}

PHP Implementation Example

The function below sends a POST request with the required headers, handles HTTP and cURL execution errors, validates the JSON parsing step, and extracts the top-level "amount" field directly.

PHP

<?php

function fetchAccountBalance(): string

{

// Define your API endpoint and bearer token securely via environment variables

$url = defined('API_BALANCE_URL') ? API_BALANCE_URL : 'https://api.example.com/v2/app/balance';

$token = defined('API_BEARER_TOKEN') ? API_BEARER_TOKEN : 'YOUR_API_TOKEN_HERE';

$curl = curl_init($url);

curl_setopt_array($curl, [

CURLOPT_RETURNTRANSFER => true,

CURLOPT_TIMEOUT => 30,

CURLOPT_FOLLOWLOCATION => true,

CURLOPT_POST => true,

CURLOPT_HTTPHEADER => [

'Authorization: Bearer ' . $token,

'Content-Type: application/json',

'Accept: application/json',

],

CURLOPT_POSTFIELDS => json_encode(['format' => true]),

]);

$response = curl_exec($curl);

$curlError = curl_error($curl);

$httpStatus = curl_getinfo($curl, CURLINFO_HTTP_CODE);

curl_close($curl);

// 1. Handle transport-level errors

if ($response === false) {

return 'cURL Error: ' . $curlError;

}

// 2. Handle non-2xx HTTP responses

if ($httpStatus < 200 || $httpStatus >= 300) {

return 'HTTP Error ' . $httpStatus . ': ' . $response;

}

$data = json_decode($response, true);

// 3. Validate JSON output

if (json_last_error() !== JSON_ERROR_NONE) {

return 'JSON Error: ' . json_last_error_msg() . ' | Response: ' . $response;

}

// 4. Extract and return the target attribute

return isset($data['amount']) ? (string) $data['amount'] : 'Amount field missing in response';

}

Usage Summary

Replace API_BEARER_TOKEN with your active API credential.

Ensure your server environment has the php-curl extension enabled.

Call fetchAccountBalance() in your application to receive either the numeric string balance or a descriptive error message if the call fails.

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