We've been told the built-in editor is going away when the new website finally happens. (Maybe somewhat soon?) The new site will include some sort of recipe editor.

Regardless of the old or new site, if you're routinely working with recipes of more than a few lines, an external editor is the way to go.

The Notepad++ editor is often mentioned. It's free, and includes features like line numbering and Lua syntax highlighting. It's a line-oriented editor, so it's suitable for programming.

I use the "vim" editor, which lets me keep my hands on the keyboard most of the time. It's not a bad option if you started out punching paper tape on a a Teletype machine.

With an external recipe editor, you can copy and paste into the Foldit editor. The more formal way is to use Load -> Import in the Foldit editor read an external file. Similarly, Save -> Export gets a recipe out of Foldit and into a file, or you can copy and paste into an external editor.