index.php

<?php
const API_URL = "https://api.bol.com/retailer";
const API_CLIENTID = "8338f293-a8a0-4d6c-b660-7d77d76002cb";
const API_SECRET = "aMPKgg6tsz_5fvRQbNweO4ejCaSdOI_cVb698D5YwfMy1GeAvm94YGeAD1JRjmI_eGKk0s2bRXc59NECLcrKSw";
const API_USER = "sync";

function bol_bearer() {
    $session = curl_init("https://login.bol.com/token?grant_type=client_credentials");
    curl_setopt($session, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
    curl_setopt($session, CURLOPT_USERPWD, API_CLIENTID . ':' . API_SECRET);
    curl_setopt($session, CURLOPT_POST, true);
    curl_setopt($session, CURLOPT_ENCODING, 'UTF-8');
    curl_setopt($session, CURLOPT_RETURNTRANSFER, true);

    $res = curl_exec($session);
    curl_close($session);
    $j = json_decode($res, true);
    if (! is_array($j)) {
        user_error("http_bearer: invalid res=$res");
    }
    if ($j["token_type"] !== "Bearer") {
        user_error("http_bearer: unsupported token type=" . $j["token_type"]);
    }
    if ($j["scope"] !== "RETAILER") {
        var_dump($j);
        user_error("http_bearer: account does not have retailer role but role=" . $j["scope"]);
    }
    return $j["access_token"];
}

function bol_http($method, $url, $bearer, $d = []) {
    $session = curl_init(API_URL . $url);
    $headers = ['Accept: application/vnd.retailer.v3+json', sprintf('Authorization: Bearer %s', $bearer)];
    if (count($d) > 0) {
        curl_setopt($session, CURLOPT_POST, true);
        curl_setopt($session, CURLOPT_POSTFIELDS, json_encode($d));
        $headers[] = 'Content-Type: application/json';
    }

    curl_setopt($session, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($session, CURLOPT_CUSTOMREQUEST, $method);
    curl_setopt($session, CURLOPT_ENCODING, 'UTF-8');
    curl_setopt($session, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($session, CURLOPT_SSL_VERIFYPEER, false);
    $response = curl_exec($session);
    curl_close($session);
    $results = json_decode($response, true);
    return $results;
}

// https://api.bol.com/retailer/public/redoc/v3#operation/post-offer-export
// Not interesting? https://developers.bol.com/documentatie/ftp/content-ftps-handleiding/
$token = bol_bearer();
$res = bol_http("GET", "/orders", $token, []);
var_dump($res);