You can call API via GET or POST requests. Set your API key as x-api-key as http header (secure method) or just include as request parameter in get or post request.
Anyone, from the most clueless amateur to the best cryptographer, can create an algorithm that he himself can not break.
Bruce Schneier (Cryptographer, computer security professional, and writer)
Comma-separated list of pages in form "1,3,4". (Only for PDF file)