PDF Max is a powerful PDF app for iPhone that allows users to read, annotate, and sign PDF documents with ease. The app offers a desktop-class experience with its smooth and responsive interface, making it easy to navigate through large PDF documents.

One of the standout features of PDF Max is its annotating capabilities, which includes text markup, threaded comments, voice annotations, handwriting with advanced zoom-in writing, eraser tools, shape tools, freetext tool, stamp tool, and signature tool. The app also includes editing features such as managing PDF pages and outlines, and managing PDF embedded links.

PDF Max also includes form-filling features that support text fields, checkboxes, radio buttons, dropdown lists, buttons, and date-time fields. The app allows users to manage their signatures and one-time signatures for customers.

The app offers a seamless, desktop-like integration with Dropbox or Google Drive and includes a local library for organizing files from different sources. Users can also copy/move files or folders between online cloud storage services and iCloud Drive support.

Overall, PDF Max is a comprehensive PDF app that is perfect for those who want to go paperless. The app offers a wide range of features that are easy to use, making it a must-have for anyone who works with PDF documents on their iPhone.