CollectionSplitPayment.php

<?php

$api_key = '4e49de80-1670-4606-84f8-2f1d33a38670';

$data  = array(
    'title' => 'Test',
    'split_header' => '',
    'split_payments' => array(
        array(
            'email' => '[email protected]',
            'fixed_cut' => '100',
            'variable_cut' => '',
            'stack_order' => '0'
        ),
        array(
            'email' => '[email protected]',
            'fixed_cut' => '100',
            'variable_cut' => '',
            'stack_order' => '1'
        )
    )
);

$parameter = http_build_query($data);
$parameter = preg_replace('/%5B[0-9]+%5D/simU', '%5B%5D', $parameter);

$process = curl_init();
curl_setopt($process, CURLOPT_HEADER, 0);
curl_setopt($process, CURLOPT_RETURNTRANSFER, true);
curl_setopt($process, CURLOPT_TIMEOUT, 10);
curl_setopt($process, CURLOPT_USERPWD, $api_key . ':');
curl_setopt($process, CURLOPT_URL, 'https://billplz-staging.herokuapp.com/api/v4/collections');
curl_setopt($process, CURLOPT_POSTFIELDS, $parameter);
$body = curl_exec($process);

echo '<pre>'.print_r(json_decode($body, true), true).'</pre>';