Facebook Unseen is a diminutive add-on for firefox that blocks Facebook's read receipts from being sent. If you don't want to have your friends knowing when or if you've read their messages, Facebook Unseen is the perfect extension to block those pesky read receipts. While others may find it handy, it can be cumbersome if you have a friend who expects you to reply immediately. Once this add-on is installed, there's nothing really much you need to do. Facebook Unseen is a small add-on that doesn't take up much room, as it only has to block a single line of code to disable read receipts from Facebook. One cool feature of Facebook Unseen is the ability to manually mark a message as read, giving you absolute control over who sees when you've read a message. This feature will help to make it look less suspicious to your friends if you reply without the read receipt showing up first. Overall, FB unseen is a simple but effective add-on that gives users more control over read receipts in Facebook chat.