1. Introduction

GNU Aspell is a spell checker designed to eventually replace Ispell. It can either be used as a library or as an independent spell checker. Its main feature is that it does a much better job of coming up with possible suggestions than just about any other spell checker out there for the English language, including Ispell and Microsoft Word. It also has many other technical enhancements over Ispell such as using shared memory for dictionaries and intelligently handling personal dictionaries when more than one Aspell process is open at once.

1.1 Comparison to other spell checker engines

	Aspell	Ispell	Netscape 4.0	Microsoft Word 97
Open Source	x	x
Suggestion Intelligence	88-98	54	55-70?	71
Personal part of Suggestions	x	x	x
Alternate Dictionaries	x	x	?	?
International Support	x	x	?	?

The suggestion Intelligence is based on a small test kernel of misspelled/correct word pairs. Go to http://aspell.net/test for more info and how you can help contribute to the test kernel. The current scores for Aspell are 88 in fast mode, 93 in normal mode, and 98 in bad spellers mode see section 4.4.4 for more information about the various suggestion modes.

If you have any other information you would like to add to this chart please contact me at kevina@gnu.org.

1.1.1 Comparison to Ispell

1.1.1.1 Features that only Aspell has

• Does a much better job with coming up with suggestions than Ispell does or for that matter any other spell checker I have seen. If you know a spell checker that does a better job please let me know.
• Can learn from users misspellings.
• Is an actual library that others programs can link to instead of having to use it through a pipe.
• Is multiprocess intelligent. When a personal dictionary (or replacement list) is saved it will now first update the list against the dictionary on disk in case another process modified it.
• Can share the memory used in the main word list between processes.
• Support for detachable dictionaries so that more than one aspell class can use the same dictionary.
• Support for multiple personal dictionaries as well as support for special auxiliary dictionaries.
• Better support for run-together words.
• Ability to use multiple dictionaries by simply specifying it on the command line or in the configuration files.
• A better, more complete word list for the English language. Word lists are provided for American, British, and Canadian spelling. Special care has been taken to only include one spelling for each word in any particular word list. The word list included in Ispell by contrast only included support for American and British and also tends to included multiple spellings for a word which can mask some spelling errors.

1.1.1.2 Things that, currently, only Ispell have

• Support for affix compression (However this will change with Aspell 0.51)
• Lower memory footprint
• Perhaps better support for spell checking (La)TEX files.
• Support for spell checking Nroff files.