SpellChecker

A free .NET Spell checker. Spell checkers are expensive and most come tied to a UI that may or may not suit your application. This spell checker was developed to run a server side spell check for a web application. It performs pretty well.

How to use the spell checker

There are a few ways to use the spell checker, but the usage is very simple and straightforward:

using (var queuedSpellChecker = new QueuedSpellChecker()) {
   var result = queuedSpellChecker.PerformSpellCheck("Spelling mispake.", 0, new List<String>());
   Assert.AreEqual(9, result.StartIndex);
   Assert.AreEqual(7, result.Length);
   Assert.AreEqual("mistake", result.Suggestions[0]);
}

The spell checker uses a WPF text box under the hood to perform the spell checking. In order for this to function correctly you need to run all of the spell checks on a dispatcher thread. This is handled for you in the QueuedSpellChecker class. If you are running a WPF application and don't mind doing your spell check on the foreground thread you can just use the SpellCheckProvider directly like so:

var spellCheckProvider = new SpellCheckProvider();
var result = spellCheckProvider.CheckSpelling("Spelling mispake.", 0, new List<String>());

See the unit tests (of which there is never enough) for some more examples of usage.

The Queen's English

Down with words like Color. Be proud of the firm tradition of excellence in language, don't let those heathen on the other side of the Atlantic destroy a beautiful thing. Pass a Boolean to only use the British (or Australian) English dictionary.

[TestMethod]
public void TestSpellCheckUsingCorrectEnglish() {
   //Pass true to use correct English, otherwise the spell checker defaults to the language settings on the local machine
   using (var queuedSpellChecker = new QueuedSpellChecker(true)) {
      var result = queuedSpellChecker.PerformSpellCheck("Color.", 0, new List<String>());
      Assert.AreEqual(0, result.StartIndex);
      Assert.AreEqual(5, result.Length);
      Assert.AreEqual("Colour", result.Suggestions[0]);
   }
}

Caveats...the catch

You need to include references to PresentationFramework and associated assemblies in order to use this (as it relies on WPF)