- Vim
- Visual Studio Code - Built-in preview with scroll sync.
- CotEditor - Plain text editor with drag in support.
- Marked 2 - Markdown previewer with custom CSS and preprocessor.
- 1Writer (iOS) - Direct iCloud & Dropbox editing with custom javascript plugins.
- Bookmarklet for markdown link of current page (Bookmarklet)
- Markdownifier (Web & Bookmarklet) - Convert web page to Markdown (Provided by Marked).
- Paste to Markdown (Web) - Copy rich text to Markdown.
Maybe Obsidian can also be taken into account