PDF Markup Tool: iAnnotate

iAnnotate is available in the Chrome Web Store.

iAnnotate is a Chrome os extension that lets you edit, markup, and annotate PDF files. It is clearly one of the easiest and fastest tools for annotating a PDF that I've seen in a long time. Its integration with Google drive is seamless, and the app saves back to your drive on exit. Three shortcomings of iAnnotate include a lack of image support, a lack of equation editor support, and the extension does not work on chrome for Mac or PC. iAnnotate works only on iOS (iPad, iPhone), Android, and Chromebook devices . PDF Escape, with its dated, clunkier interface, fills the gaps left by iAnnotate by offering better functionality, and better support for Macs and PCs. I learned about iAnnotate through an OMG! Chrome! post.