ASP.NET Spell Checker for Web Applications – RapidSpell Web .NET

By: Keyoti  06-Dec-2011
Keywords: Browsers, Spell Check

RapidSpell Web .NET provides developers with a cross browser ASP.NET spell checking control that requires no client installation, no special security settings and as much programmatic flexibility as you want.

Written for .NET in C#, RapidSpell Web .NET includes 2 interfaces, an inline highlighter and a fast (no post back) dialog interface. Includes 5 English dictionaries, including 140,000 word U.S + U.K. dictionaries (separate and combined), plus Canadian and Australian English.


Quick designer based usage with the flexibility of code-behind access

All the features of a regular Windows spell checker

Comprehensive ASP.NET text box support (plain, rich, custom)

Inline (as you type style) spell checking

RapidSpellWInline provides a Windows style in-text-box spell check control, with editable text box support for modern browsers and static 'overlay' support for older browsers. AJAX is used to highlight spelling errors within the text box.

Traditional spell check dialog box

The RapidSpellWebLauncher control provides traditional dialog (modal/non-modal) spell checking. The preview box displays the context of each sentence while misspelled words are highlighted and underlined.

Open API, for customization and non GUI usage

Use the open API to customize core behavior, allowing you to meet the individual needs of your ASP.NET web application, eg;

  • User dictionary behavior - eg. change the way the user dictionary is persisted (databases, Cache etc)
  • Parser behavior - eg. use UI as an offensive language checker
  • Custom ignore patterns

The included non GUI component provides core spell checker functionality through the RapidSpellChecker class, which means it is suitable for ASP.NET server applications as well as any console application. It has been clocked at 70,000 words/sec on a standard 1GHz PC (100k+ on average server hardware).


RapidSpell Web .NET supports Internet Explorer 5+, Firefox 1, Chrome, Opera, and Safari on the PC and Mac. It uses only HTML and Javascript, this means there are no special requirements, plugins, or long downloads, as with some spell check server Controls.

It’s easy to use the ASP.NET spell checker as a Web Control in an aspx page or programmatically in code behind, either way full customization of style, layout and properties is possible. Using a simple HTML template mechanism it is also possible to layout the spell checker as you wish, including branding.

All dictionaries (main and user's) are stored on the server, yet the user's spell checking experience is not hampered by any post-backs to the server, because there are none. User dictionaries can be stored on a database (examples provided).

Dict Manager, allows RapidSpell Dict files to be customized and created from other word lists, using the free 'Dict Manager' tool distributed with the product.

RapidSpell Web .NET provides two distinct spell checker controls;
RapidSpellWebLauncher functions in one of two modes, 'popup' - which open's a small console window with the spell checker in it or in 'separate' - which loads the spell checker in the main window on a separate page, there are no restrictions with either of these modes.
RapidSpellWInline works using AJAX to highlight errors inside the text box.

All of the included spell checker controls can be enabled as Validators, which perform validation of spelling in text boxes before allowing data to be saved. For example; when the form is posted back, the RapidSpellWebLauncher or RapidSpellWInline control will check for errors, if there are errors the user is prompted (in the validation summary) to run a spell check. They do not have to correct all errors, but must at least run the spell checker. The spell checker can also be started automatically.

Two powerful suggestions engines can be used to find suggestions for words;

Phonetic suggestions algorithm (English only), works well with genuine attempts to spell correctly.

Hashing suggestions (default), roughly 40 times faster than the phonetic algorithm, works best on typographic errors and commonly misspelled words.

RapidSpell Web .NET has a decoupled checker engine, which allows (via an interface definition) the use of any core spell checker class or other type of text parser to be used with the interface. This allows complete customization of the engine (including for tasks other than spell checking, such as to check for offensive words) and the interface.

The RapidSpell ASP.NET control works without session variables, making it possible to use RapidSpell Web .NET with server clusters/farms. The single request architecture keeps server load down, and is possible through our high performance suggestions algorithm

RapidSpell Web .NET was written entirely in C#, and makes no use of legacy DLLs or APIs.

Every aspect of the appearance (text, layout, and style) can be customized through simple properties. The user interface can easily be changed to predefined language text or individually customized with your own wording.

Open API allows the user dictionaries to be stored in any fashion desired - default is server file based, however this can be overridden for database, or application cache usage for example.

RapidSpell Web .NET is designed to ASP.NET 1.0, 1.1, 2.0, 3.0, 3.5 and 4.0 specification and are all fully supported - as are all versions of Visual Studio .NET.

Keywords: Browsers, Spell Check

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