Are you a developer looking to incorporate Thai spellchecking to your website? Try my JavaScript module.
Spellchecking extension for Thai language for Firefox.
https://addons.mozilla.org/en-US/firefox/addon/thai-spellchecker/
This extension finds and highlights spelling mistakes for Thai language in Firefox. It uses a reduced and modified version of LibThai to find mistakes. Some frontend JavaScript code is taken from LanguageTool.org extension.
A demo is available here: https://wishawa.github.io/thai-spellcheck-extension/