Editable Rich Text

If your requirements are simple enough (and/or your userbase is savvy enough) you could manually build a parser, with certain markup clarified in the instruction field or similar, and a rich text "preview" field to show the user what they will expect upon submission.

Unfortunately not - the end user base is public and training them on a markup language isn't feasible.

I think you mean something like a markdown format.. I have seen some posts on Appian forum and I think there is a component which allows entering the text in markdown format.

Hi,

You can use webComponent field, and call Rich Text Editor Online service (you can find any trustable sites on internet easily), inside a webComponent
or Create custom HTML/CSS code Rich Text Editor, call the custom code in webApi (body).

Thanks

The idea of using webComponent is good.
But - there is a problem.

If we want the rich text which users enters back into Appian local variables/PVs, the webcontent component cannot help.
I don't see any option to retrieve those values back. If the requirement is not to get this data into Appian local variables then this option is good.

Other suggestion of custom HTML/CSS is doable but I see too much efforts.
Because you will have to then go embedded Appian route, then pass the data back to Appian once user enters the rich text.

It would really be helpful if Appian had a native SAIL component for this. As seen from the comments here - many are interested in having this SAIL component. We also will have to think how will the formatting of rich text be sent back to Appian.
The entered text can be returned to Appian in html format (with simple tags like bold, italic, underline, headings etc supported).