Because I seem to be unable to write a blog post about this tool, I'll notify you of the existence of the Malagasy online spell checker in a telegraphic style.

Malagasy Online Spell Checker is an online spell checker that you can use for free. Just go to http://dotmg.net/spell/check, input the malagasy text you want to check into the textarea and click on the button you see. The software will respond back with the list of words that could be misspelled. It won't propose any correction yet. It doesn't have an exhaustive list of correct spellings, so maybe some of the words it says misspelled aren't really misspelled.

Malagasy Online Spell Checker is opensource, and is released under the terms of the GNU Affero General Public License, version 3 (or above). It is part of a larger project called tsipelina, and the project is available on tsipelina.sourceforge.net. Malagasy Online Spell Checker requires PHP and a webserver, as it is written in PHP. You may need a Subversion client to download the source if you want to.