Seen Blocker for Facebook is a Firefox extension designed to enhance user privacy by preventing the 'Seen' status from being displayed when reading messages on Facebook. This tool is particularly useful for those who wish to read messages without notifying the sender. The extension can be easily activated with a single click on the toolbar button, which changes color to indicate its active status. Once activated, it effectively blocks the necessary web requests to ensure that read receipts are not sent.

This subscription-based extension retains its activation status across browser sessions, allowing users to maintain their privacy effortlessly. The installation process is straightforward, requiring minimal setup after the initial download. With Seen Blocker for Facebook, users can engage with their messages without the pressure of immediate responses, making it an essential tool for many social media users.