Stop Facebook from marking messages as 'Seen'
Prevent Facebook from telling your friends you've read their messages with this browser extension.
Remember when you could read a Facebook message and ignore it, without thinking twice about replying? Then Facebook rolled out read receipts for Facebook Messages, thus forcing your hand to reply. Luckily, there's now a browser extension to disable the "Seen" notification on messages you've read, as reported by The Next Web.
The browser extension is called Chat Undetected, and was developed by Crossrider. It's compatible with Chrome, Firefox, and Internet Explorer. I was unable to install the extension in Safari, even though The Next Web report lists it as a compatible browser.
To install the extension, visit this Web page from a compatible browser and follow the instructions. It's a small extension; you shouldn't have any issues getting it installed.
After the extension is installed, you can read a Facebook message and not have to feel compelled to respond immediately. Keep in mind, however, any message you read on your iPhone or Android device will still be marked as read. This extension will only work when you're using Facebook Chat from the Web site.