Caps Lock Notifier is a Firefox add-on designed to improve user security while entering passwords. This subscription-based tool adds a visual cue to password fields, indicating whether the Caps Lock key is activated. When users hover over the icon, a tooltip appears, alerting them that 'CAPS LOCK is on!' This feature helps prevent users from inadvertently entering passwords incorrectly due to the Caps Lock being enabled.

The add-on requires permission to access data for all websites, allowing it to detect password fields across different pages. Importantly, it does not collect or store any user data, ensuring privacy while enhancing security. Users can also review the source code on GitHub, providing transparency about its functionality and security measures.