PDF Viewer is a small, smart PDF all-rounder. Through document merging, replies, and reviews, image editing, and much more, the app supercharges mobile PDF workflows. Assemble PDF files from individual documents on your iPhone, iPad, or Mac with ease, and open files from emails, websites, or cloud services such as Dropbox, Google Drive, OneDrive, or Box.

What we love: You can easily highlight and mark up text while reviewing a document, and leave comments by adding a note, images, or even audio.

Quick tip: Pro subscribers have access to the password-protection functionality, which enables you to add user and owner passwords and limit permissions.

Meet the creator: The PSPDFKit team work remotely and are all passionate about technology and building PDF solutions that power successful projects. Their mission is to help businesses work more smartly, save time, and effectively replace the need for paper processes.