This is a simple terminal multiplexing utility for Node.js environments. It is inspired by the awesome and unreachable tmux native Unix utility. The stmux utility is intended to provide just a very tiny subset of the original tmux functionality, but in a portable way for bare Node.js environments and with some special features for application build environments. Most notably, stmux has a built-time error detection and notification feature, can automatically restart terminated commands, and can automatically close or wait after all spawned commands have successfully or unsuccessfully terminated. Internally, stmux is based on the awesome Blessed screen rendering environment and emulates full XTerm-compatible pseudo-terminals to the spawned programs with the help of Blessed XTerm and the underlying XTerm.js terminal rendering and node-pty pseudo-terminal integration modules.