Looks really slick!
You should consider adding word support. Support for office XML formats[1] are simple enough to hand-roll.
[1]:https://en.wikipedia.org/wiki/Microsoft_Office_XML_formats
You should consider adding word support. Support for office XML formats[1] are simple enough to hand-roll.
[1]:https://en.wikipedia.org/wiki/Microsoft_Office_XML_formats
As a developer, I would ideally recommend to look into using a custom internal representation for a document and developing converters that convert between your representation and various formats. This way you won't be hindered by limitations of a specific format.
However, if you lack the resources to develop and maintain these converters yourself, look into the feasibility of leveraging LibreOffice by using a preexisting format like WordProcessingML as an internal format. You can then use LibreOffice to handle the conversion between the various formats you want to support. The downside to this is that you'll eventually outgrow WordProcessingML if you want to support futures not supported by that specific format.