Polar Markdown

zacharysarette

Polar Markdown — a blazing-fast desktop markdown editor and viewer with live preview, Mermaid diagrams, and split-pane editing. Built with Tauri 2 + Svelte 5.

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Polar Markdown

A blazing-fast desktop markdown editor and viewer with live preview and diagram support
Built with Tauri 2 + Svelte 5 + TypeScript — ~5 MB app, ~40 MB RAM

Write, edit, and view markdown with live-rendered Mermaid diagrams, split-pane editing, full-text search, and instant file watching — all in a native app that starts in under a second.

Features

	Feature	Description
Editor	Split-pane	CodeMirror 6 editor with live preview side-by-side
Editor	Auto-save	Saves automatically after 1s, or immediately with Ctrl+S
Editor	Scroll sync	Editor and preview scroll together proportionally
Editor	Active line	Cursor position highlights the matching element in the preview
Rendering	Markdown	Syntax-highlighted code blocks, tables, and full formatting
Diagrams	Mermaid	Live SVG flowcharts, sequence diagrams, ER diagrams, and more
Diagrams	ASCII Art	svgbob renders box-drawing characters and `bob`/`svgbob` code blocks
Search	Full-text	Search across all markdown files with line-number results
Layout	Multi-pane	Open up to 4 files side-by-side (Ctrl+Click, Ctrl+W, Ctrl+1-4)
Navigation	File tree	Expand/collapse, keyboard nav, arrow-key auto-select
Folders	Native picker	Open any directory on your system
Sorting	Flexible	Sort by name (A-Z / Z-A) or modification time (newest / oldest)
Filter	Filename	Instantly narrow down files by typing
Watch	Live reload	Sidebar and content update when files change on disk
Help	Built-in	Click the `?` button for an embedded user guide
State	Persistence	Remembers folder, file, panes, and sort mode across sessions
Platforms	Cross-platform	Windows, macOS, and Linux

Getting Started

Prerequisites (all platforms)

Node.js v20+
Rust (latest stable)
GitHub CLI (gh) — for releases only

Windows

WebView2 (pre-installed on Windows 10/11)
Visual Studio Build Tools with the "Desktop development with C++" workload

macOS

Xcode Command Line Tools:
```
xcode-select --install
```

Linux

Install the required system libraries:

Debian / Ubuntu:

sudo apt install libwebkit2gtk-4.1-dev libappindicator3-dev librsvg2-dev patchelf

Fedora:

sudo dnf install webkit2gtk4.1-devel libappindicator-gtk3-devel librsvg2-devel

Arch:

sudo pacman -S webkit2gtk-4.1 libappindicator-gtk3 librsvg

Install dependencies

npm install

Development

npx tauri dev

This starts both the Vite dev server (with hot reload) and the Tauri native window.

Build

npx tauri build

Build output by platform:

Platform	Artifacts	Location
Windows	NSIS installer (.exe), MSI installer	`src-tauri/target/release/bundle/nsis/`, `msi/`
macOS	DMG disk image, .app bundle	`src-tauri/target/release/bundle/dmg/`, `macos/`
Linux	.deb package, AppImage	`src-tauri/target/release/bundle/deb/`, `appimage/`

Note: Tauri does not support cross-compilation. Each platform must be built on native hardware.

Run tests

# Frontend tests (vitest)
npx vitest run

# Rust tests
cd src-tauri && cargo test

# Type checking
npx svelte-check

Releasing

Single platform (Windows)

release.bat 0.2.0

Builds the app, commits, pushes, and creates a GitHub Release with Windows installers.

Multi-platform workflow

Each platform must be built on native hardware. Order doesn't matter — whichever runs first creates the release, the rest upload artifacts.

# 1. On Windows:
release.bat 0.2.0

# 2. On macOS:
git pull && ./release.sh 0.2.0

# 3. On Linux:
git pull && ./release.sh 0.2.0

Both scripts are safe to run — they contain no secrets and rely on your local gh CLI session for authentication.

Tech Stack

Layer	Technology
Desktop framework	Tauri 2.10
Frontend	Svelte 5 (runes), TypeScript
Bundler	Vite 6
Backend	Rust
Markdown	marked + highlight.js
Editor	CodeMirror 6 (markdown mode, one-dark theme)
Diagrams	mermaid (flowcharts, etc.), svgbob (ASCII art)
File watching	notify (Rust, native OS APIs)
Testing	vitest + @testing-library/svelte, cargo test

Project Structure

src/                        # Frontend (Svelte + TypeScript)
  App.svelte                # Root component — pane state, folder selection
  lib/
    components/             # Sidebar, FileTree, FileTreeItem, MarkdownViewer,
                            # MarkdownEditor, EditablePane, ContentArea,
                            # SearchResults
    services/               # filesystem, persistence, markdown, tree-utils,
                            # sort, highlight
    types.ts
src-tauri/                  # Rust backend
  src/
    lib.rs                  # Tauri app setup
    models.rs               # FileEntry model
    commands/
      filesystem.rs         # Directory tree, file read/write, search, help content
      watcher.rs            # Native file system watcher
      diagram.rs            # svgbob ASCII → SVG conversion
docs/                       # In-app documentation (viewable in Polar Markdown)
release.bat                 # Windows release script
release.sh                  # macOS / Linux release script

License

MIT

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