$apiToken = 'YOUR_TOKEN';
$inputFile = fopen(base_path('input.vtt'));
$response = Http::acceptJson()
->withToken($apiToken)
->attach('subtitle', $inputFile)
->post('https://subtitletools.com/api/v1/convert-to-srt');
$json = $response->json();
if ($json->errors) {
throw new RuntimeException();
}
$response = Http::acceptJson()
->withToken($apiToken)
->get($json->download_url);
$outputFilePath = base_path('output.srt');
file_put_contents($outputFilePath, $response->body());