The best alternatives to NovelPad are Dillinger, Pine, and Iceberg Editor. If these 3 options don't work for you, we've listed a few more alternatives below.
Iceberg is a beautiful & entirely customizable markdown editor for crafting articles in WordPress. Iceberg leverages the best of WordPress, and the best of the new block editor, while getting out of your way–allowing you to focus on publishing your next post.
Write.md is an easy to use markdown editor tool that automatically creates a document URL to make sharing and collaboration quick and easy. No need fo an account to get started.