1. Open the app
2. Drag a folder containing documents onto the app icon, or use File > Open and choose a folder
3. It shows you words not in the spelling dictionary
4. Add words to the ignore list (cmd-I), or fix spelling errors externally
5. Reload the list with cmd-R

Supported document types: plain text, Microsoft Word, Rich Text Format, HTML

Magic Spell saves settings by creating a Magic Spell config.json file in folders you open. If you delete this file, settings such as ignored words and files will be lost.