Enchant is described as 'On the surface, Enchant appears to be a generic spell checking library. You can request dictionaries from it, ask if a word is correctly spelled, get corrections for a misspelled word, etc'. There are five alternatives to Enchant for a variety of platforms, including Linux, Online / Web-based, Windows, Mac and iPhone. The best alternative is Druide Antidote. It's not free, so if you're looking for a free alternative, you could try Hunspell or GNU Aspell. Other great apps like Enchant are ispell (Free) and myspell (Free, Open Source).
GNU Aspell, usually called just Aspell, is a free software spell checker designed to replace Ispell. It is the standard spell checker for the GNU software system. It also compiles for other Unix-like operating systems and Windows.
Ispell is a program that helps you to correct spelling and typographical errors in a file. When presented with a word that is not in the dictionary, ispell attempts to find near misses that might include the word you meant.