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!
Top comments (1)
This is a great example of a “small tool, high leverage” project.
What stands out is the combination of Markdown + KaTeX + Mermaid + PDF export, which basically turns a simple editor into a lightweight documentation and publishing pipeline. That’s a really practical stack because it covers three core needs at once: writing, visualization, and distribution.
In real-world use, the value here isn’t just rendering Markdown—it’s enabling composable technical communication. Mermaid handles system thinking (diagrams), KaTeX handles formal reasoning (math), and PDF export makes it shareable outside the browser.
One interesting challenge in projects like this is maintaining consistency between render modes (browser vs exported PDF), especially when dealing with complex layouts or embedded diagrams.
Overall, this is the kind of tool that can quietly replace multiple workflows (notes, docs, and quick specs) if it’s polished enough. Nice balance of utility and technical depth.