Cocoa programs automatically inherit spell checking technology by Apple. The spell checker in Mac OS X 10.4 and higher does a better job dealing with LaTeX commands, but the Apple spell checker does not understand LaTeX commands and marks many of them as misspelled. However, other spelling services can be added to the Apple technology; they then become available in all Cocoa programs.

TeXShop supports continuous spell checking, which can be toggled on or off with a menu command. A preference item selects the initial position of this toggle.

Aspell is "a more intelligent Ispell" for Unix machines written by Kevin Adkinson. His program has been ported to Mac OS X and made into a spelling service by Anton Leuski. The new speller supports LaTeX. To obtain it, go to

  http://cocoaspell.leuski.net/

An alternate LaTeX spell checker named Excalibur is often used. This spell checker was written by Rick Zaccone; it can open TeXShop files. To obtain it, go to

  http://www.eg.bucknell.edu/~excalibr/excalibur.html

Basic Help
Checking Spelling