Hidden Text Detector (HTD) is a Windows application designed to identify and reveal concealed text in PDF, Word, and Excel documents. This tool is essential for document analysis, compliance verification, and security auditing. The application detects hidden content using advanced heuristics, including microfonts (less than 4pt), white or near-white text, and documents with hidden text attributes. This helps users uncover potentially concealed information that may not be immediately visible. Use Cases: Document forensics, compliance auditing, intellectual property protection, and transparency verification. This tool is intended for legitimate purposes such as security research, document verification, and compliance checking. Users are responsible for ensuring they have proper authorisation to analyse documents.