Marked 3

TL;DR

It is a dedicated preview window for Markdown files so you do not have to keep guessing what your README or blog post looks like while typing.

Who is this actually for?

Technical writers and developers who live in minimal text editors like Vim or Sublime and need a robust, live-updating visual check.

The Good

• Handles custom CSS and multiple Markdown flavors without breaking a sweat.
• The scroll-sync is actually reliable, unlike most free browser extensions I have tried.

The Catch (Potential Downsides)

It is a paid utility in an era where VS Code and Obsidian provide decent previews for free. You really have to care about typography and document export to justify the extra window.