Mer is a discontinued free and open-source software distribution, targeted at hardware vendors to serve as a middleware for Linux kernel-based mobile-oriented operating systems. It is a fork of MeeGo.

Some goals of the project are:

Mer is not an operating system; it is aimed to be one component of an operating system based on the Linux kernel. Mer is a part of the operating system above the Linux kernel and below the graphical user interface (GUI).

Mer just provides the equivalent of the MeeGo core. The former MeeGo user interfaces and hardware adaptation are to be done by various other projects and by hardware manufacturers, which will be able to build their products on top of the Mer core.

There is support for systemd, Wayland, Hybris, and other current FOSS software.

Zephyr is an attempt at creating a stack for use by other projects to be exploring lightweight, high-performance, next-generation UIs based on Mer, Qt5, QML Compositor and Wayland.

Weston 1.3, which was released on 11 October 2013, supports libhybris, making it possible to use Android device drivers with Wayland.

Mer can be compiled for a number of instruction sets such as x86, ARM or MIPS.