ConPTY

ConPTY, short for Windows Pseudo Console, is a Windows API introduced by Microsoft to enable modern terminal emulation by providing a pseudo terminal that connects a host process to a child process running a console application. It is designed to give terminal applications a stable, high-level interface for handling input, output, and sizing, while allowing the host to render the terminal UI.

ConPTY was released as part of Windows 10 and has been used to support contemporary terminal experiences on Windows, including Windows Terminal. It provides a separation between the host application (such as a terminal emulator) and the console application running inside the pseudo console. This design allows host processes to interpret and render ANSI escape sequences, manage line discipline, and implement features such as resizing and input handling without requiring direct access to the child process’s console subsystem.

In operation, a host creates a pseudo console object and sets its initial screen size. It then establishes bidirectional communication channels (often via pipes) to connect the host with the guest process, which runs a command-line application with its standard input and output redirected to the pseudo console. The host is responsible for presenting the terminal UI to the user and for propagating user input to the guest process, while the guest writes output that the host renders. The host can resize the pseudo console, and the guest process receives these events, allowing dynamic terminal sizing.

ConPTY has been integral to modern Windows terminals, such as Windows Terminal, and is used to support compatibility with traditional console applications while enabling enhanced rendering and richer terminal features on Windows.