Tetris-playing computer programs have recently become more popular with the development of Zetris (mat1jaczyyy), a port of MisaMino (misakamm) to the official Tetris game Puyo Puyo Tetris. Since then, new programs have been developed such as Cold Clear (MinusKelvin), Tetras (traias), Wataame (ameyasu), and Hikari (SoRA_X7). Currently, all of these independently solve the problem of interfacing with the host game. This duplicates a lot of work between these projects, especially since this interfacing code is generally not made public due to concerns about such programs being used to cheat in online Tetris games. This repository aims to specify a common interface for communication between a Tetris-playing program and a Tetris frontend, similar to how the Universal Chess Interface solves a similar problem for Chess.