Several libraries are available to do spell-checking related tasks: Enchant and gspell.
Enchant provides a low-level API. You can ask it if a word is misspelled,
or ask for suggestions for a misspelled word. On a higher level, gspell
integrates spell-checking for GTK+ text widgets (both GtkEntry
and GtkTextView
).
In GNOME, those libraries get used in text-heavy applications like gedit (a text editor) and Epiphany (a web browser, for text entry in web forms).
Enchant home page
gspell home page