Guide

1. Install

1. Buy SSEM MarkdownEditor on the Mac App Store (US$0.99, one-time purchase). The App Store link works once the app has been approved.
2. Open it from the Applications folder or Launchpad. Requires macOS 14 Sonoma or later.
3. The preview loads its rendering libraries from the internet (jsDelivr CDN), so make sure you are online when you first use it.

2. Create, open and save

• New document: ⌘N. Or start from File › New from Template: README, Meeting Notes, Technical Documentation, Blog Post, Project Proposal, API Documentation or Changelog.
• Open: ⌘O, or drag a .md file onto the window.
• Recent files: File › Open Recent. Clear Recent Files empties the list.
• Save: ⌘S. Documents are saved where you choose (or in iCloud Drive).

3. Views and themes

• Use the view buttons at the top right of the window or the shortcuts: Editor Only (⌃⌘1), Editor and Preview (⌃⌘2), Preview Only (⌃⌘3).
• In split view, the editor and preview scroll together.
• Pick a preview theme — GitHub Dark, GitHub Light, Notion or Paper — from the Template menu at the bottom right.
• Change the editor’s colors in View › Syntax Theme.

4. Mermaid diagrams

Set a code block’s language to mermaid and the preview draws the diagram.

```mermaid
graph TD
    A[Open document] --> B{Contains Mermaid?}
    B -->|Yes| C[Render diagrams]
    B -->|No| D[Render Markdown only]
```

5. Diagram Studio

• Edit an existing diagram: double-click it in the preview, or choose Diagram › Edit First Diagram in Document….
• New diagram: Diagram › New Diagram in Diagram Studio… (⇧⌘D). When you apply it, it’s inserted as a code block at the editor’s cursor.
• Visual editing (flowcharts): add, rename and delete nodes and choose from 9 shapes (Rectangle, Rounded, Stadium, Subroutine, Database, Circle, Decision, Hexagon, Flag). Give connections one of 6 line styles and a label, and switch the layout direction (Top → Down, Left → Right, Bottom → Up, Right → Left).
• Canvas: click a node to select it. In Connect mode, click two nodes in turn to link them. Zoom in, zoom out and zoom to fit.
• Code mode: edit any Mermaid type — sequence, class, state, ER, Gantt, pie, mindmap and more — and the canvas re-renders as you type. You can also start from a starter template.
• Export: PNG Image (2×), SVG Vector, or Copy as PNG to the clipboard.
• Apply or cancel: Apply (⌘↩) replaces the diagram’s code block in your document. Cancel (esc) closes without changing the document.

6. Math and code

• Math is rendered with KaTeX: inline with $...$ or \(...\), display with $$...$$ or \[...\].
• Add a language name to a code block (e.g. swift, python, json) for syntax highlighting in 15+ languages. Every block gets a copy button.

7. PDF export and printing

• File › Export as PDF… (⇧⌘E)
• File › Page Setup… (⇧⌘P), File › Print… (⌘P)

8. iCloud

File › iCloud › Save to iCloud saves to the app’s iCloud Drive folder, and Open iCloud Folder in Finder shows that folder. If iCloud Drive is off you’ll see “iCloud is not available” — turn on iCloud Drive in System Settings › Apple Account › iCloud.

9. Keyboard shortcuts