Matterhorn

Matterhorn is a terminal‑based client that connects to the Mattermost chat platform, allowing users to interact with their teams from a Unix command‑line environment. After launching the binary, the program prompts for the server URL and credentials, then provides a full‑screen interface with markdown rendering, thread participation, and emoji reactions. It supports multiple teams, channel creation and membership management, and secure handling of passwords and authentication tokens through external commands such as the macOS keychain.

The client offers extensive keyboard‑driven functionality, including configurable keybindings, readline‑style editing, and tab‑completion for usernames, channels, commands, emojis, and fenced code block languages. Optional features include live message preview, smart quoting, spell‑checking via Aspell, syntax highlighting for code blocks, and mouse support in compatible terminals. Users can also upload and download attachments, mute channels, flag posts, and customize notifications with external scripts.

Matterhorn runs on macOS and other Unix‑like systems, requiring only the ncurses‑compat‑libs package on CentOS Stream 8. It is distributed as pre‑built binaries and can be installed via third‑party Snap packages. The software is stable and maintained with documentation, FAQs, and a developer community on the Mattermost server.