A plain-text file written in markdown, normally with the .md extension. It uses simple characters like # and - to mark headings and lists.

How do I open an MD file on a Mac?

Right-click it, choose Open With, and select TextEdit or a markdown app. It is plain text, so any text editor works.

Is an MD file the same as a text file?

In structure, yes. Both are plain text; the .md ending tells apps the content uses markdown conventions.

Can I open an MD file in Word?

Word may open it as plain text, but it will not render the formatting. Convert it to DOCX first, for example by exporting from a markdown app or with Pandoc.

Is .markdown the same as .md?

Yes. Both extensions mean a markdown file; .md is simply shorter and far more common.

Why does my MD file look like it has random symbols?

Those symbols are markdown syntax. A markdown app such as atiea shows them styled, with headings, lists and checkboxes rendered.

What Is an MD File? How to Open One on Mac

Quick answer

An MD file is a plain-text file written in markdown, usually ending in .md. On a Mac you can open it with TextEdit, any code or text editor, or a markdown app such as atiea.

You downloaded a file ending in .md and your Mac is not sure what to do with it. The short version: it is a plain-text file, it is safe to open in any text editor, and a markdown app will make it far easier to read. This guide covers what is inside, how to open it, and what to do when it looks odd.

What is an MD file?

An MD file is a text file written in markdown, a lightweight syntax that adds structure with ordinary characters: # for headings, - for lists, **double asterisks** for bold. The .md ending tells apps to treat the text as markdown. Some files use the longer .markdown extension, which means the same thing.

You will meet MD files in three places: README files in software projects, documentation sites, and personal notes. Because the format is only text, the file is tiny, opens in anything, and will still be readable in decades. If you want the syntax itself, the markdown cheat sheet covers it.

What does an MD file look like inside?

# Project notes

Draft status: **in progress**

## Tasks

- [ ] Write the intro
- [x] Choose a title

## Links

See [[Reading list]] for background, or the
[style guide](https://example.com/style).

| File     | Owner |
|----------|-------|
| intro.md | Sam   |

Opened in a plain text editor, you see exactly the characters above. Opened in a markdown app, the heading is large, the tasks are checkboxes, and the table is a grid. The file itself does not change either way; only the display does.

Note that markdown has several dialects. Tables and task lists such as - [ ] come from extended flavors, and [[wiki links]] are a notes-app convention rather than part of core markdown. A file using them still opens fine anywhere; unsupported pieces simply show as plain characters.

How to open an MD file on Mac

Right-click the file, choose Open With, then pick TextEdit or another text editor.
Use a markdown app for live syntax highlighting. atiea is a native Mac app built for this.
From Terminal: open -a TextEdit notes.md opens it in TextEdit, and open notes.md uses the default app.
Just read it in Terminal: cat notes.md prints the file, and less notes.md lets you scroll (press q to quit).

To make double-click always use the same app, select the file, press Cmd+I (Get Info), choose an app under Open with, and click Change All.

If TextEdit shows something strange

TextEdit defaults to rich text for new documents. If you plan to edit an MD file there, choose Format, then Make Plain Text (Shift+Cmd+T) before saving, or the app may try to save it as RTF. For anything beyond a quick look, a dedicated editor avoids the problem.

Reading vs editing

A plain text editor shows the symbols as they are, which is fine for a short README but tiring for long documents. A markdown editor styles the text as you read it, and a preview pane shows the final rendered result. atiea highlights markdown as you write, so a long note stays easy to read while you edit it.

Keep in mind that opening a file in an app and storing a note in an app are different things. Check how your chosen app handles files before assuming it works with a folder of MD files you already have; check each product’s site for current details.

Troubleshooting common problems

The file has no .md ending. Finder may be hiding extensions. In Finder settings, under Advanced, turn on showing all filename extensions.
Double-click opens the wrong app. Use Get Info and Change All, as described above.
Characters look garbled. The file may use a different text encoding. Most modern MD files use UTF-8, which most editors assume by default.
Everything shows as one long line. Markdown joins single line breaks inside a paragraph. A blank line starts a new paragraph, so the file may just be written that way.
Images are missing. MD files usually reference images by path or URL. If the image files were not shared with the MD file, the preview will show a broken image.

MD file vs other formats

Format	Best for	Opens in
.md	Writing and notes you want to keep portable	Any text editor
.txt	Unformatted text	Any text editor
.docx	Documents with layout, shared with Word users	Word and compatible apps
.pdf	Fixed layout for reading and printing	Preview and browsers

An MD file is the same as a text file in structure; the extension signals the markdown conventions. For a deeper look at why people choose it for notes, see how to take notes in markdown.

Converting an MD file

If you need to send the contents to someone who does not use markdown, convert it. atiea exports to Markdown, HTML, PDF and DOCX, and the guide to converting markdown to PDF or Word covers other routes, including Pandoc.

When not to use an MD file

Complex layouts. Multi-column pages, precise spacing and print design belong in a layout tool.
Heavy collaboration with non-technical editors. Tracked changes and comments are easier in a word processor or a cloud workspace such as Notion.
Databases. Markdown is text, not structured data.

For everyday writing, notes and documentation, though, markdown is hard to beat. If you want a Mac app for it, see the atiea features, the best markdown notes apps for Mac, or the glossary for terms used here.

Is it safe to open an MD file?

Yes. An MD file is text, and opening it in a text editor does not run anything. The usual caution applies to files from unknown senders in general: a file named notes.md that is really something else would not open as readable text. If the contents look like normal words and symbols, it is a normal markdown file. Links inside it are only links; they do nothing until you click them, so check where they go first.

Creating your own MD file

You can make one in any text editor by saving a plain-text file with a .md name. In a notes app you simply write a note. In atiea, press Cmd+N for a new note, write with markdown, and use Cmd+B, Cmd+I and Cmd+K for bold, italic and links. Notes are stored locally on your Mac, with no account required. You can export a note to Markdown, HTML, PDF or DOCX when you need a file to share.

A good first exercise is a short README for any folder of work:

# Tax documents 2026

What is in this folder and what is still missing.

## Done
- [x] Income statements
- [x] Receipts, Jan to Jun

## Missing
- [ ] Receipts, Jul to Dec

Anyone who opens that file, on any computer, can read it without special software. That portability is the main reason the format is so widely used. If you are comparing how different apps treat markdown, see the Apple Notes alternative page for one example of a notes app that is not markdown-native.