MrkToolsEvery save becomes a version
Saves, and rewrites from outside the app, automatically become timestamped versions. Put any two side by side and only the changed words are marked. In a Git repo, HEAD joins the same list.
Markdown · macOS
Your AI said “updated the README.” See exactly what changed, and where.
A macOS Markdown viewer and editor that keeps a timestamped version of every save — and of every rewrite from outside the app. Git is optional.
Free forever · signed and notarized / $19 One-time · up to 2 Macs per license
Features
Nothing lost when AI rewrites the file
If an agent rewrites the file while you are editing, MRDown neither reloads over you nor overwrites. Last save / on disk / my edits sit in three columns, and only conflicting lines are marked.
Compare any two files, as they are
Press ⌘⇧D and pick two files. Read word-level differences in the same view as the timeline. Two .docx files show the diff between document versions.
Read it, just read it
Tables, code, Mermaid, KaTeX and footnotes render cleanly. One column by default, a reading mode that hides the rest, and .docx files open as Markdown.
AI explains the diff
Let AI describe what changed between two versions. Anthropic, OpenAI and Gemini use your own API key (BYOK); Ollama and Apple’s on-device model need no key and stay on your Mac.
Inspect the document, fix in one go
⌘⇧L runs the open document through markdownlint and lists line, problem and rule. “Fix” and “Fix all” go through normal editing, so ⌘Z undoes them. The line-length rule — which hits nearly every Japanese line — is off by default.
Open over SSH · search whole folders
Open and save user@host:/path Markdown. Folder-wide search handles partial Japanese matches too.
The Markdown editor basics are covered too
Versioning is the headline, but MRDown is built to hold up as the tool you read and write in every day. Everything below is in free MRDown.
Mermaid
Mermaid diagrams, rendered in place
Mermaid code blocks render as diagrams — flowcharts, sequence, class and ER diagrams, Gantt charts and more. A syntax error shows the error and keeps the source, so your document never breaks. You can also turn a table into a Gantt chart.
```mermaid
flowchart LR
Draft --> Review --> Release
```
Read
- Tables, quotes, syntax-highlighted code
- KaTeX maths, footnotes, task lists
- Local images (relative paths)
- Outline (table of contents) that follows you
- Reading mode (⌘⇧M)
- GitHub Light / Dark preview themes
- Auto-reload when the file changes on disk
Write
- One-column live editing, or side-by-side
- Formatting toolbar (bold, headings, lists, links…)
- “/” menu for tables, checklists, code, WBS
- List continuation and auto-closing brackets
- Paste images and URLs
- Table column edits, bullets → table
- Character and word counts
Manage
- Multiple documents with session restore
- Open a folder with a file tree
- Find & replace in the document (⌘F)
- Search across open tabs (⌘⇧F)
- Drag & drop, “Open with…”
- Drop a .docx to open it as Markdown
Export & stay safe
- HTML / PDF export
- Sanitized HTML and a strict CSP (safe for untrusted files)
- Move to Trash (recoverable)
- Japanese / English UI
- Keyboard shortcut cheat sheet
Pricing
MRDown
Write, read, keep versions.
Free
Free forever · signed and notarized
MIT License · Source on GitHub
The MRDown name and logo are not covered by the MIT license
- History, two-version diff, compare with HEAD
- Three-column view for outside rewrites
- Compare any two files
- Live split preview, folder tree, find & replace
- Search that normalizes Japanese variants
- HTML / PDF export
MrkDown
Read what a change means.
$19
One-time · up to 2 Macs per license
- Everything in MRDown
- AI diff explanation (5 providers, incl. no-key on-device)
- Document inspection (markdownlint) with fix-all
- Remote Markdown over SSH (coming)
- Whole-folder search (coming)
- Refund within 30 days if it doesn’t work · Apple Silicon · macOS 13+
MRDown vs MrkDown
| MRDown | MrkDown | |
|---|---|---|
| Version history, diff, restore | ✓ | ✓ |
| Three-column view for outside rewrites | ✓ | ✓ |
| Compare any two files | ✓ | ✓ |
| Compare with local Git | ✓ | ✓ |
| Open folders / search open documents | ✓ | ✓ |
| AI diff explanation (BYOK / on-device) | — | ✓ |
| Document inspection (markdownlint) with fix-all | — | ✓ |
| Remote Markdown over SSH | — | Coming |
| Whole-folder search (unopened files too) | — | Coming |
| Price | Free | $19 one-time |
Start with free MRDown.
MrkDown has no separate trial — free MRDown is the trial. If it fits, add Pro with a one-time purchase.
Download MRDown