2) Annotation Tool: Crocodoc

According to Crocodoc's web,

• Crocodoc converts Microsoft Office and PDF documents to HTML5 so users can view them right in their web app.

Crocodoc's viewer is able to:

1. Easy integration within your web app
   • No plugins, downloads, or desktop software required
2. Fast, crystal-clear rendering
   • HTML5 & CSS3
3. Advanced security & flexible deployment options
   • Document not able to view until you set up a session
   • Pre-user permissions when viewing, creating, or deleting annotations
4. Fully customizable look & feel
   • Integrate with almost any kind of platform
   • Ex. Dropbox integration
   • Ex. Edmodo, the leading social platform for educators
5. Mobile device support
   • Supports Apple, Android, and Kindle
6. Built-in commenting & markup tools
   • Add & Reply to comments
   • Supports real-time collaboration
   • Real-time notifications when annotations are created

In addition, Crocodoc allows user to download annotated PDF copies of any document.

Best for: Presentation(Main), collaboration

One drawback: Unable to add new pages.