Originally published at htpbe.tech . The version on htpbe.tech stays in sync with the latest detection algorithm — refer to it for the canonical text. Receiving a PDF document — whether it is an invoice, contract, certificate, or legal document — often comes with an implicit trust that what you see is what was originally created. But what if someone modified the file before it reached you? How can you tell if a PDF has been edited? This question matters more than ever. Document fraud is on the rise, with criminals modifying PDFs to change payment details, alter contract terms, or forge certificates. According to research from Forensic Focus , PDF manipulation detection has become a critical skill for anyone handling important documents. The good news is that you do not need to be a cybersecurity expert to check if a PDF has been edited. This guide will walk you through five practical methods, from simple checks anyone can do to advanced automated tools.…