After the Deadline is a free REST based service that provides Spelling, Style, and Grammar checking support to any application that has Internet access. For personal use developers may use the free online server hosted by After the Deadline. Commercial users need to host their own server, the software for which is being offered under the GNU General Public License.
After the Deadline currently offers plugins for Firefox, Google Chrome, WordPress, and OpenOffice.org. With a couple lines of JavaScript After the Deadline’s spelling and grammar checker can be applied to all the textarea tags on a webpage.
Currently there is no support for clients written in .NET or Java so developers for these platforms will have to build their own UI. Arik Poznanski has created a basic C# wrapper around the REST calls, which he then used to build a Windows Live Writer plugin that does just that. Miguel Ventura has created a wrapper for Python and Michael Sepcot for Ruby.
Even when using raw REST calls the API is very easy to use. Simply pass in an application ID and the block of text to be checked and it returns a list of errors with suggestions. A second call can be made to get an explanation for the error.