Barrier is a software application that allows users to share a single keyboard and mouse between multiple computers. It's essentially a software-based KVM (Keyboard, Video, Mouse) switch, enabling seamless control of different machines with a single set of peripherals. The repository, hosted on GitHub, contains the source code, documentation, and build instructions for Barrier. It's a fork of the original Synergy project, addressing some of its limitations and offering improvements.

The core functionality of Barrier revolves around a client-server architecture. One computer acts as the server, connected to the physical keyboard and mouse. The other computers, acting as clients, connect to the server over a network (typically a local area network). The server captures the keyboard and mouse input, and then transmits this data to the appropriate client based on the mouse cursor's position on the screen. When the cursor moves to the edge of the server's screen, it effectively "jumps" to the screen of a connected client, allowing the user to control that machine. Similarly, keystrokes are directed to the active client.

The repository provides the source code for both the server and client components, written primarily in C++ and using the Qt framework for the graphical user interface. This allows for cross-platform compatibility, with builds available for Windows, macOS, and Linux. The project's structure is well-organized, with clear separation of concerns between the core logic, network communication, and user interface elements. The build process utilizes CMake, a cross-platform build system, making it relatively straightforward to compile and install Barrier on different operating systems.

Key features of Barrier include secure communication through encryption, clipboard sharing for text and images, and support for multiple monitors on both the server and client machines. The configuration is flexible, allowing users to customize the screen layout, hotkeys, and other settings to suit their specific needs. The project also includes documentation, including a comprehensive README file and wiki pages, which provide detailed instructions on installation, configuration, and troubleshooting.

Compared to its predecessor, Synergy, Barrier has undergone significant improvements. These include enhanced security features, improved performance, and a more user-friendly interface. The developers have actively addressed bugs and implemented new features based on community feedback. The project is actively maintained, with regular updates and contributions from a community of developers. The repository also includes issue tracking, allowing users to report bugs, request features, and contribute to the project's development.

In essence, the Barrier repository provides a complete solution for sharing a keyboard and mouse across multiple computers. It's a well-maintained, open-source project that offers a practical and efficient way to control multiple machines with a single set of peripherals, making it a valuable tool for users who work with multiple computers simultaneously. The project's focus on cross-platform compatibility, security, and ease of use makes it a compelling alternative to proprietary KVM solutions.