縦書き変換プラグイン is a free Chrome add-on developed by Mat'z. This program allows users to convert their text into vertical writing format, primarily intended for use in X. It serves as a tool for transforming posts into vertical writing, catering to specific needs such as avoiding search indexing and preventing usage as training data for AI generation.

The latest version, Ver1.1, introduces support for line breaks and variable vertical character count. Additionally, it provides partial compatibility with emojis, enhancing the overall user experience. With its easy-to-use interface and seamless integration with Chrome, 縦書き変換プラグイン offers a convenient solution for those looking to convert their text into vertical writing format.