common

Comments on every website
share advice, better deals, browsing tips and opinions…

common's main view screenshot

Read helpful comments from other people
Get discounts, scam warnings, hints to navigate a site…

Add to Google Chrome
Using Firefox, Safari or Explorer? Drag and drop [common] to your bookmarks bar

common is free, no account needed
Add the extension and you are ready to go

common is a browser tool that lets you post notes in any web page and read notes from other people.

Store private notes by unchecking Share with everyone.

Vote notes Up and Down to sort them out.

What can I comment on?

Anything you want. Here's some ideas: