Search for "merge PDF" or "compress image" and you will find dozens of free websites ready to help. Drag, drop, download, done. It is so convenient that most people never ask the obvious question: where did my file just go? For a holiday photo, maybe it does not matter. For a passport scan, an employment contract, a medical report or a bank statement, it matters a lot. How most free converters work The typical flow is simple: Your file is uploaded to the provider's serv...