GRSMD: Instant Markdown Viewer — Local & Private
Published: (February 28, 2026 at 09:38 PM EST)
2 min read
Source: Dev.to
Source: Dev.to
Overview
GRSMD (GoodRelax Simple Markdown Renderer & Viewer) is a single index.html file that opens in your browser. Drop a .md file onto it or paste with Ctrl + V—it renders immediately. No npm, no build step; all libraries are loaded from CDNs and rendering happens locally (except PlantUML).
Live demo:
Source code:
Features
| Feature | Library | Processed locally? |
|---|---|---|
| Markdown | marked.js 17.0.1 | Yes |
| Mermaid diagrams | mermaid.js 11.12.2 | Yes |
| Syntax highlighting | highlight.js 11.11.1 | Yes |
| LaTeX math | KaTeX 0.16.28 | Yes |
| PlantUML | plantuml.com | Consent required* |
* PlantUML is the only feature that contacts an external server. A confirmation dialog appears before any data is sent; you can cancel it and the rest of the document will still render.
Usage
- Multiple tabs – Press [New Tab] to open several documents in separate browser tabs.
- Drag & drop – Drop
.mdor.txtfiles onto the editor or preview area. - Paste – Press Ctrl + V to paste Markdown directly into the editor.
- Zoom & pan – Use Ctrl + Scroll to zoom diagrams (0.5× – 5.0×), drag to pan, double‑click to reset.
- Scroll preservation – Re‑rendering does not jump you back to the top.
- Privacy – Nothing leaves your browser unless you explicitly allow it (PlantUML).
Long‑press the [?] button for AI‑powered productivity help.
Samples
- Quick sample:
- Full sample (Mermaid + PlantUML + LaTeX):
Drop any of the sample files onto the live page to see the renderer in action.