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MarkdownReader // built by coslu labz

The Markdown editor that fits in 3.8 MB.

Tauri + Rust, no Electron, no cloud, no login. Split-pane, full GFM, Shiki syntax highlighting — the same engine VS Code uses. Sub-second cold start, 80 MB RAM at idle.

MarkdownReader · split-pane editor with live preview
fig. 1 · MarkdownReader · split-pane editor with live preview
§ 01
why

Markdown editors became browsers in disguise.

The ecosystem gives you two options: heavyweight Electron (Obsidian, Typora — 200 MB+ baseline) or tools that barely render beyond plain text. We wanted something that opens in under a second, uses 80 MB of RAM, and renders full GitHub-Flavored Markdown. So we built it.

§ 02
features

What this product actually does.

№ 01

Live split-pane

Editor on the left, preview on the right, in real time. CodeMirror 6 + Allotment — the same combo serious IDEs use.

§ № 02

Full GitHub-Flavored Markdown

Tables, task lists, strikethrough, footnotes, emojis, anchors. markdown-it with the mature plugin ecosystem — no toy parser here.

| col | val |
|---|---|
№ 03

Shiki syntax highlight

The same engine VS Code runs. Code blocks in the preview are pixel-identical to your favorite editor.

№ 04

Native shortcuts

Ctrl+N new · Ctrl+O open · Ctrl+S save · Ctrl+Shift+S save as. The exact behavior Windows expects.

№ 05

File association

Registers `.md`, `.markdown`, `.mdown`, `.mkd`, `.mdx`. "Open with → MarkdownReader" right from Windows Explorer.

№ 06

Auto dark/light

Follows the OS theme automatically. No manual switch, no saved preference — Windows decides.

§ 03
under the hood

Why these technical choices.

01 Tauri 2 · Rust · WebView2

Why Tauri (not Electron)

Electron bundles the entire Chromium (~150 MB). Tauri uses WebView2 already shipped with Windows — only your app gets distributed. Result: a 3.8 MB installer instead of 150+.

02 CodeMirror 6

CodeMirror 6 — IDE-grade editor engine

The same engine powering Replit, Codepen, Discord, Sourcegraph. Long-text performance, robust undo, real extensibility. Not a fancy textarea.

03 Shiki · markdown-it

Rendering faithful to GitHub and VS Code

markdown-it covers 100% of the GFM spec. Shiki ports the VS Code tokenizer to the browser via TextMate grammars — the highlight is the same, not an approximation.

§ 04
specs

The spec sheet.

Installer size
3.8 MB
Disk footprint
~11 MB
Idle RAM
~80 MB
Cold start
< 1s
Platforms
Windows 10/11 · x64
License
MIT
Current version
v0.1.0
§ 05
roadmap

Where we are · where we’re going.

  • [×] Split-pane editor + preview done
  • [×] Live preview done
  • [×] Syntax highlight (Shiki) done
  • [×] GitHub-Flavored Markdown done
  • [×] File association + Open With done
  • [ ] Mermaid diagrams planned
  • [ ] Export to PDF planned
§ 06 · next The next COSLU product. JarvsTranscript