Unfortunately, there is no fully developed and completely proof-tested instrument application for spell-checking Arabic. The language is extremely complex in both its vocabulary, and its writing. Because of its highly inflected character, it proves enormously difficult for a program to identify spelling errors in Arabic, especially since many of its written characters change their shape dramatically depending on their position within the word, as well as the nature of the other characters beside them.
There has been at least one comprehensive attempt to develop such a piece of software. Several Arab Computer Scientists and Linguists from the University of Cairo have worked on such a program, and although their results are promising, the application is far from ready for commercial use and distribution. Their work is documented in a paper that you may access at http://www.claes.sci.eg/NARIMS_upload/CLAESFILES/3847.pdf
One of the best manners to circumvent the problem is to use a comprehensive English-Arabic translator, such as Golden Al-Wafi, whose description is available at this URL: http://golden-al-wafi-translator.software.informer.com/ , and which you may download from http://www.atasoft.com/ .
