Advanced Text Editor Upgrade

I'm seeking to enhance the functionality of my current design tool. The particular aspect of concern is text editing - right now, changing the font affects all text within a box instead of allowing individual characters or words to be customized in terms of font, size, and style. I aspire for functionality similar to that of Canva.com, where varied styles can be applied within one text box.

Key Features Required:
- Text individuality: The ability to treat text elements as separate entities.

Capabilities Required:
- Expertise in Canvas and related technologies.
- Extensive experience in designing and developing custom web tools.