PDF Expert is a PDF editing and management platform developed by Readdle. It is available for macOS and iOS devices and is designed to provide users with a range of tools and features for working with PDF files. PDF Expert allows users to view, annotate, edit, and manipulate PDF documents. Some of its key features include the ability to highlight text, add comments and annotations, fill out forms, merge and split PDFs, sign documents electronically, and more. It is known for its user-friendly interface and powerful capabilities, making it a valuable tool for professionals and individuals who frequently work with PDF files.