xterm

The foundational terminal emulator for the X Window System, providing robust DEC VT102 and Tektronix 4014 emulation since 1984.

Xterm remains the gold standard for terminal emulation, maintained by Thomas Dickey and serving as the reference implementation for terminal features. It handles complex character sets through UTF-8 support, manages 256-color palettes, and offers precise mouse tracking for CLI tools like Vim or Tmux. While modern wrappers exist, xterm provides the core logic (and the ubiquitous libXft integration) that ensures consistent command-line performance across Unix-like environments.

https://invisible-island.net/xterm/