# Marksidian — Product Facts

Machine-readable fact sheet. Last updated: 2026-09-04.

## Product

- Name: Marksidian
- Category: Markdown editor (desktop application)
- Platform: macOS only (Apple Silicon and Intel)
- Minimum OS: macOS 11 or later (Electron 33 requirement)
- Developer: Dorin Ciobanu (solo developer)
- Current version: 0.3.16 (September 2026)
- Built on: Electron, CodeMirror 6, markdown-it
- Tests: 900 Playwright end-to-end tests across 37 suites, run against the built app
- Website: https://marksidian.idv4.com/
- Distribution: direct download (.dmg, about 100 MB) and Homebrew (`brew install --cask dciobanu/tap/marksidian`); not yet notarized — the first launch needs `xattr -cr /Applications/Marksidian.app` or System Settings > Privacy & Security > Open Anyway

## Pricing

| Plan | Price | Covers | Notes |
|---|---|---|---|
| Single | $19 one-time | 1 Mac | Every update through 1.x included |
| Three Macs | $39 one-time | 3 Macs | Every update through 1.x included |

- Payment processor: Stripe
- Trial: the download is public (GitHub releases, Homebrew); the purchase is the license; 14-day refund
- Subscription: none
- Account required: none
- Activation server: none — the receipt is the license

## Editing modes

| Mode | Shortcut | Behavior |
|---|---|---|
| Live Preview | View menu or status bar | Content renders as you type; the actively edited line reveals raw markdown syntax |
| Source | View menu or status bar | Raw markdown exactly as stored on disk |
| Reading | Shift+Cmd+E | Fully rendered document, same layout as Live Preview |

Live Preview / Source: toggle from the View menu or the status bar (keyboard shortcut listed in Help > Keyboard Shortcuts). Reading: Shift+Cmd+E.

## Feature summary

| Feature | Supported | Detail |
|---|---|---|
| Live Preview editing | Yes | Content renders as you type; active line shows syntax |
| In-place table editing | Yes | Type into rendered cells; add rows/columns; only the edited cell changes in the source |
| Math (KaTeX) | Yes | Inline `$...$` and block `$$...$$`; click a rendered equation to edit its source |
| Mermaid diagrams | Yes | Rendered as SVG; click to edit source |
| Whole-document auto-format | Yes | Option+Shift+F: consistent bullet markers, renumbered ordered lists, aligned table pipes, collapsed blank-line runs, trailing spaces removed; fenced code and math are left alone; Cmd+Z undoes |
| Command palette | Yes | Cmd+Shift+P lists every command with its shortcut and jumps to headings |
| Print and export | Yes | Cmd+P prints the Reading rendering; File > Export writes PDF or a standalone HTML file |
| Heading folding | Yes | Cmd+Option+[ and Cmd+Option+], plus Fold All / Unfold All; the document is not modified |
| Spell check | Yes | System spell check while typing, native right-click suggestions (View > Check Spelling While Typing) |
| Rich-text paste | Yes | HTML on the clipboard is converted to Markdown on paste |
| Images | Yes | Drag or paste an image; it is saved beside the document and the link is inserted |
| Callouts | Yes | `> [!NOTE]` style callouts in Live Preview and Reading |
| Footnotes | Yes | Rendered, with jumps between reference and definition |
| Code blocks | Yes | Syntax highlighting in all three modes, language badge, copy button, fence-language autocompletion |
| Multi-cursor | Yes | Cmd+D adds the next occurrence |
| Find and replace | Yes | Cmd+F in the editor with an "n of m" readout; in-place find bar in Reading |
| Community themes | Yes | 700+ themes; browse, install, and manage (Cmd+,) |
| Outline / heading navigation | Yes | Collapsible tree, resizable persistent width |
| Session restore | Yes | Files, cursor, scroll, mode, zoom |
| Source-aware line numbers | Yes | Optional in all modes |
| External file-change reload | Yes | A file edited by an agent or another tool reloads in place; with unsaved edits the window asks first ("Reload from Disk" / "Keep My Changes") |
| `.md` file association | Yes | Registers as a handler for `.md` files |
| Vault / graph / plugins | No | Not a PKM app; edits plain files |
| Sync service | No | Files stay on disk |
| Windows / Linux | No | macOS only |

## File handling

- Format: plain `.md` files anywhere on disk; no proprietary database or import step
- The app does not import, index, or move anything
- Uninstalling the app leaves all documents untouched

## Network access

| Case | When | Detail |
|---|---|---|
| Theme gallery | Only when the user browses or installs a community theme | Theme list, `theme.css`, `manifest.json` and screenshots are fetched from GitHub |
| Remote images | When a document contains an `https:` image URL | The image loads like it would in any renderer |
| Theme CSS | Never | Installed theme CSS is sanitized: `@import` is removed and `url()` references outside a small allowlist are neutralized, so a theme cannot fetch fonts, images, or stylesheets |

There is no telemetry, no account, and no activation server.

## Support

- Purchases and refunds: reply to the Stripe receipt; refunds within 14 days, no questions asked
- Bug reports: no public tracker yet; reply to the receipt
- Downloads and release notes: https://github.com/dciobanu/marksidian-releases/releases