ST Writer is a word processor program for the Atari ST series of personal computers. It was introduced by Atari Corporation in 1985 along with the 520ST. It was a port of Atari's enormously successful AtariWriter Plus from the earlier 8-bit computer series, matching it closely enough to share files across the platforms with no changes. Running on the ST allowed it to display a full 80-column layout, create much larger files, and support additional features.