$curl = curl_init();
curl_setopt_array($curl, [
    CURLOPT_URL => 'https://www.cheap-pdf.com/generate-pdf-public',
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_POST => true,
    CURLOPT_POSTFIELDS => [
        'fileorhtmlorurl' => '
Hello World
',
        'apikey' => '.2qEZ£Jzby8D(W-Bw*+dR2l%h*',
        'filename' => 'example.pdf',
        'width' => 500,
        'height' => 500
    ]
]);
$response = curl_exec($curl);
curl_close($curl);

import requests

url = 'https://www.cheap-pdf.com/generate-pdf-public'
files = {
    'fileorhtmlorurl': '
Hello World
',
    'apikey': '.2qEZ£Jzby8D(W-Bw*+dR2l%h*',
    'filename': 'example.pdf',
    'width': 500,
    'height': 500
}

response = requests.post(url, headers=headers, files=files)

const FormData = require('form-data');
const fs = require('fs');
const fetch = require('node-fetch');

const form = new FormData();
form.append('fileorhtmlorurl', '
Hello World
');
form.append('apikey', '.2qEZ£Jzby8D(W-Bw*+dR2l%h*');
form.append('filename', 'example.pdf');
form.append('width', 500);
form.append('height', 500);
fetch('https://www.cheap-pdf.com/generate-pdf-public', {
    method: 'POST',
    body: form
})
.then(response => response.json())
.then(data => console.log(data));