I built a browser-based Markdown Previewer with KaTeX, Mermaid and PDF export

Hey everyone,

I've been building Run It Free — a collection of privacy-focused online tools.

One tool I recently launched is a Markdown Previewer designed to make writing technical content easier.

Features:
• Live split-screen preview
• GitHub Flavored Markdown
• KaTeX math support
• Mermaid diagrams
• Export to PDF / .md
• Syntax highlighting
• Zen writing mode
• Browser-only processing (no uploads)

The goal wasn't to replace IDEs but to create a lightweight editor that opens instantly and works everywhere.

Would love feedback:

What would make you switch from your current Markdown workflow?
Missing features?
UI improvements?

Tool:
runitfree.online

Thanks!