i3lock

i3lock is a lightweight screen locker designed for Linux desktop environments that use the i3 window manager. It replaces the visible desktop with a secure lock screen and prompts the user for a password to unlock the session. Although developed in the i3 ecosystem, i3lock is usable with other X11-based window managers and does not depend on i3 itself.

The default i3lock interface is minimal: a plain screen with a simple password prompt. It delegates authentication to the system's PAM (Pluggable Authentication Modules), so unlocking requires valid user credentials. The program itself does not manage user sessions beyond presenting the lock screen; it exits when authentication succeeds, returning control to the user.

For richer visuals, many users install forks such as i3lock-color, which extend i3lock with options for background images, blur effects, color themes, and on-screen text. These forks are separate projects but compatible with the same locking workflow and PAM integration.

Usage and configuration: i3lock is typically launched by the user or bound to a keybinding in the window manager, and it runs until a correct password is entered. It targets the X11 display server and, on Wayland systems, can run under XWayland, but it is not a native Wayland lock screen.

History and licensing: i3lock originated as part of the i3 window manager project and is maintained by the open-source community as a lightweight, minimal alternative to full-featured screen lockers.