SpellServer.NET 2.0   
by Chado Software, Inc.   

A lightning-fast spell checking .NET object, packaged with two complete ASP.NET applications (one in C#, one in VB.NET), SpellServer.NET has built-in customizable dictionaries for US English, UK English, French and Spanish.

Server-side checking means that your users don't have to download or install any software, and spell checking is available to all users, regardless of which browser they use.

Includes a Performance Test tool that you can use on your own systems, with your own text, to determine the performance you'll see in the real world.

Using SpellServer.NET is as simple as incorporating a single aspx into your existing web application. We supply detailed instructions on the incorporation, and how to customize the page so it looks and acts just how you want it to. Using Web Forms with Code Behind, the form and content of the page are completely separated.

Lifetime free upgrades and tech support. No royalties.