SharedDoc is an online document platform that lets anyone upload a document online and then share the file to a community, so they can add comments. We have 500 free invites for TechCrunch readers here.

Once you upload a Word or Google Docs document to SharedDoc’s platform, you can send email invites to a friends or colleagues to comment on the document. In order to comment, a user needs to set up an ID. Users can then highlight portions of the the document where they’d like to leave a comment and post their input.

Comments can be seen by by everyone invited on the document and commenters can respond to others comments. Each comment carries the ID of the user, and the date of posting. SharedDoc also creates a permanent record of the comments by saving or printing the document with the comments as footnotes.

The idea of commenting about documents isn’t new. SharedDoc will face competition from startups Etherpad, DocStoc, and Scribd, to name a few. And SharedDocs will compete with the collaboration features of Google Docs (and perhaps Microsoft Office soon).