Terminal UI
A terminal UI (TUI) renders an interactive interface in a text terminal — laying out boxes, text, and widgets in a grid of character cells and handling keyboard/mouse input — rather than in a native GUI or a browser. It’s a distinct rendering surface for a UI framework: the component model and declarative approach carry over, but the “pixels” are cells and the constraints (monospace grid, limited color, redraw cost) are the terminal’s.
Modern TUI toolkits increasingly reuse web-UI machinery: opentui runs React and SolidJS reconcilers against a native terminal-rendering core, so building a terminal app looks like building a web app (declare components, let a reconciler diff and update). OpenTUI even ships a WebGPU renderer so the same component tree can display in a browser — evidence the terminal is becoming one surface among several for a single UI description, not a separate discipline.
TUIs matter for developer tools and, increasingly, AI coding agents whose front-end is a terminal (OpenTUI is used by the OpenCode agent) — a seam to the agent-ready-ui thread.