Kami. So that prompted me to publish this updated post about Kami. Kami is a service that enables users to annotate and comment on PDFs. You can do this directly on the Kami website or in Google Drive with Kami's Chrome extension. Kami also works with Word and Pages files.
Here's a couple of updated videos about how Kami works.
Kami's core service for drawing, commenting, and annotating PDFs is free for all users. Kami does offer the option to upgrade to a premium account. The premium version includes options for adding voice comments and video comments to your PDFs. The premium version also supports conversion and use of Word documents.