md — Support

Last updated: 14 July 2026 · Applies to: md 1.2 — the Markdown editor published by nettrash on the App Store, running on iPhone, iPad (iOS / iPadOS) and Mac (a native macOS app).

md is the simplest Markdown editor for iPhone, iPad and Mac: write Markdown on one side and see it rendered on the other, with a warm typewriter look. Version 1.2 adds a writer mode for whole books, A4 PDFs and EPUB export, math and diagrams, a table of contents, private author notes and a live word count. This page is the single place to reach the developer for issues, general feedback, or feature requests, and to find answers to common questions before you do.

Contact

md is built and maintained by an independent developer. The fastest way to get a reply is by email; please include your platform (iPhone / iPad / Mac), your OS version, and the app version.

For privacy-specific questions, see the Privacy Policy; the same email address handles those requests.

What md does

• Opens, edits and saves .md / .markdown files (and plain text) through Apple's document system — in Files / Finder or your own iCloud Drive, with autosave. Files written in legacy encodings (Windows-1251, or UTF-16 with a byte-order mark) open and round-trip correctly.
• Renders a live preview covering headings, bold / italic / inline code / links / strikethrough, bullet / numbered / task lists (with nesting), fenced code blocks, block quotes, GitHub-style tables, thematic breaks, and images — including images your document references by remote URL.
• Draws TeX / LaTeX math ($…$, $$…$$, ```math) and Mermaid, PlantUML and Graphviz diagrams. These render on your device, offline, from engines bundled inside the app.
• Offers three layouts — Edit, Split (side by side) and Preview — with the editor and preview scrolling in sync in Split. Split needs a wide window: it appears on iPad (and in landscape), and always on Mac; on iPhone you switch between Edit and Preview. Your chosen layout is remembered.
• Shows a table of contents (Contents), a list of your private author notes, and a live word and character count.
• Prints, shares or exports the rendered document as a PDF of real A4 pages, or shares the raw Markdown source.
• Writer mode: open a folder as a book — subfolders are chapters, Markdown files are articles — create, rename, reorder and delete them, compile the whole book to one PDF, or export it as EPUB 3.
• Ships built-in example documents and a sample book you can unpack and edit (Examples).

Frequently asked questions

How do I create a new document?

On Mac: use File → New (⌘N), then save anywhere with File → Save (⌘S). On iPhone / iPad: tap Create Document in the document browser. If a brand-new device has never been signed in to iCloud Drive and the local storage location hasn't finished initializing, the very first "Create Document" right after install can briefly report "the operation couldn't be completed" — wait a few seconds after first launch, or tap again, and it will create the file. On a device signed in to iCloud this doesn't happen.

Where are my files stored?

Wherever you put them. md never moves your documents to a server — there isn't one. Files live on your device or Mac, in Files / Finder, or in your own iCloud Drive if you choose that location. A book is likewise just a folder you chose, and its chapters and articles are ordinary folders and .md files you can open in any other app. See the Privacy Policy for details.

How do I rename or move a document?

On Mac, use the title-bar menu (click the document name) or the Finder for Rename, Move To and Duplicate — these are native macOS document commands. On iPhone / iPad, rename and move in the Files app or the document browser; the app also offers a Rename… command in its share menu.

What is writer mode, and how do I start a book?

A book is simply a folder you pick: its subfolders are chapters, the Markdown files inside are articles, and they are ordered by file name (a numeric prefix like 01-intro.md first, then alphabetically). Nothing is imported or copied into the app.

On Mac: File → New Book… creates one, File → Open Book… opens an existing folder, and File → Show Book (⇧⌘B) brings the book window back. On iPhone / iPad: the launch screen offers Show Book, Open Book… and New Book… next to New Document (on a narrow screen they may sit behind a More… button); tapping an article opens it in the editor. The same actions live in the editor's Book menu.

Inside a book you can create, rename, reorder (Move Up / Move Down) and delete chapters and articles. Reordering is written back to the file names — the group is renumbered with 01-, 02- prefixes — so the order is real and visible in Finder or Files, not a private list kept by the app.

How do I turn a book into a PDF or an EPUB?

With a book open, use Share Book as PDF / Export Book as PDF… to compile the whole book into a single PDF — a title page, then every chapter and article in reading order, each starting on a fresh page — or Export as EPUB… to package it as a standard EPUB 3 with a proper table of contents, which opens in Apple Books and other readers. Math and Mermaid / PlantUML diagrams are rendered by md's own offline engines and embedded as images, so they show up in any reader. On Mac these commands are in the File menu (and in the book window's share menu); on iPhone / iPad they are in the book navigator's share menu.

What do printed and exported PDFs look like?

Real A4 pages, produced by the system print engine — the same output whether you print, share the rendered PDF, or use Export as PDF…. Pagination is line-aware, so no line of text is sliced in half at a page boundary. (A single diagram taller than a page can still be split across pages — there is nowhere else for it to go.) Put \newpage (or \pagebreak) on a line of its own to start a fresh page exactly where you want one; the preview shows it as a dashed rule.

Printed and exported pages are always white with dark ink, whichever theme you write in — a manuscript prints as a manuscript. The warm paper and the dark theme are for the screen. The old "one long content-tall page" export (and the "PDF Layout" setting that chose it) was removed in 1.2.

Where did the Mac window's toolbar go?

In 1.2 the document window has no toolbar — the menu bar is the chrome, as on a Mac it should be. View switches Edit / Split / Preview (⌘1 / ⌘2 / ⌘3), the Go menu jumps to headings, to your private notes and between a book's articles (⌃⌘↑ / ⌃⌘↓), and File carries the book, share, export and print commands. Document windows and the book window can also go full screen (the green button, ⌃⌘F). The book window keeps its own workspace toolbar.

How do math and diagrams work — do they need a network?

No. md bundles the rendering engines inside the app and runs them in the preview's web view on your device: KaTeX for math, Mermaid, Viz.js / Graphviz and PlantUML for diagrams. Nothing is downloaded at run time and nothing is sent to a diagram service — it works in airplane mode. See the Software Bill of Materials below.

What are private author notes?

An HTML comment on a line of its own whose text begins with note: — for example <!-- note: rewrite this scene --> — is treated as the writer's private note. It is listed in the Notes menu, jumps you to that spot in the editor, and never appears in the preview, the PDF, the EPUB or print. A comment written inline, inside a paragraph, is not a note and still renders as part of the text.

My Markdown punctuation isn't being "corrected" — is that a bug?

No, that's intentional. md edits Markdown source, so it deliberately turns off smart quotes and dash substitutions — your ", -- and ... stay literal so the syntax isn't corrupted.

Why doesn't the preview show some advanced Markdown feature?

md's renderer covers everyday Markdown plus the common GitHub extensions (task lists, tables, strikethrough, fenced code). It is a faithful, fast preview rather than a full CommonMark engine, so a few rarely-used constructs may render as plain text. If something common renders wrong, please report it (see Contact).

Does md collect any data about me?

No. md contains no analytics, no advertising or tracking SDKs, and there are no servers operated by us. Its App Store privacy label is "Data Not Collected", with no tracking.

Then what does md use the network for?

Exactly one thing: fetching an image that your own document references by a remote URL (![…](https://…)). That happens when the image is drawn — in the preview, and also when you print or export to PDF or EPUB. The request goes to whatever host your document names, and that host sees your device's IP address, just as it would if you opened the same URL in a browser. It carries no identifying data beyond a normal HTTP request, and no data of yours is ever sent anywhere. Documents with no remote images make no network requests at all.

What does md store on my device besides my files?

Only a few small settings, all local, none personal, none transmitted: your Edit / Split / Preview layout; and, when a book is open, a pointer to the folder you picked (a security-scoped bookmark), which article you had open last, and — on Mac — whether articles open in separate windows. Closing the book discards the folder pointer. Full details are in the Privacy Policy.

Reporting a bug

When emailing about a bug, the following details speed things up:

• Platform and OS version (iPhone / iPad → Settings → General → About; Mac → Apple menu → About This Mac).
• The md app version.
• What you did, what you expected, and what happened instead.
• If reproducible, a screenshot or short screen recording.

Public bug reports and feature discussion are welcome at the GitHub issue tracker linked above.

Feature requests

Suggestions are read and appreciated. Send them by email or open a GitHub issue tagged enhancement. Not every request will be implemented, but every one is considered.

Software Bill of Materials

The app itself is written against Apple's frameworks (SwiftUI, UIKit / AppKit, WebKit, UniformTypeIdentifiers) with a hand-written Markdown parser, and depends on no third-party Swift packages — there is no SwiftPM or CocoaPods manifest to resolve.

It does, however, bundle four open-source JavaScript engines, which render math and diagrams inside the preview's web view, on device and offline:

• KaTeX — TeX / LaTeX math.
• Mermaid — Mermaid diagrams.
• Viz.js / Graphviz — Graphviz (DOT) graphs.
• PlantUML — PlantUML diagrams.

They ship inside the app bundle; nothing is downloaded at run time and no rendering is done on anyone's server. The same engines produce the images embedded in exported PDFs and EPUBs.

On Mac the app runs in the App Sandbox and holds exactly three entitlements: user-selected file read/write (com.apple.security.files.user-selected.read-write), printing (com.apple.security.print), and network client (com.apple.security.network.client) — which a sandboxed WKWebView requires in order to launch at all, and which is also what fetches the remote images your documents reference.

The full source is published at github.com/nettrash/md (iOS / iPadOS) and github.com/nettrash/md.macOS (macOS).