Verbum provides you a solution building vertical writing images with the library of PHP GD.
On iOS platform a native app is designed for better user experiences. At this time, customized color settings have not been provided.
If you need help, you can seek help through email.
Project Verbum is provided under GPL-v3.0. The project itself does not provide any resources, while the deployed service does. Several fonts are collected and provided for design your work, and all of them are able to use free. However, you may need to take note of the mark within the font name for some special restricts. If any user uses Verbum to design and produce works, he(she) should take full responsibility for his(her) own action and generated works, nothing to do with Verbum.