縦書きコピー (Vertical Text Copy) is a free Chrome add-on developed by zaki3mymy. This add-on allows you to easily copy selected text and convert it into vertical writing format, which can be pasted into various applications. It is particularly useful when you want to post vertically-oriented text on social media platforms like Twitter.

With 縦書きコピー, you can convert any selected text into vertical writing format and copy it to your clipboard. The add-on treats whitespace as full-width spaces, ensuring accurate formatting. Whether you want to add a unique touch to your social media posts or simply experiment with different writing styles, 縦書きコピー offers a convenient solution.

Please note that 縦書きコピー is only available as a Chrome add-on and can be installed from the Chrome Web Store. It is compatible with the Chrome browser on various platforms.