Plain text & portable
An .md file is just text. It opens anywhere, has no proprietary format, and stays readable for decades - nothing locks you in.
What is an .md (Markdown) file?
An .md file is a Markdown file - a plain-text document that uses lightweight symbols like # for headings, **bold**, and - lists to represent formatting. It was created by John Gruber in 2004 as a format that stays easy to read in its raw form, and today it's everywhere - documentation, notes, and especially AI tools.
Readable as-is
Markdown's symbols are chosen to look like what they mean: # for a heading, **bold**, - for a list. You can read the raw file and still follow it.
Renders to rich text
Point it at the right editor and ## Heading becomes an actual heading, **bold** becomes bold - the symbols disappear and you see a formatted document.
You'll find .md files as README.md on GitHub, in docs and specs, in notes apps like Obsidian and Bear, and increasingly from AI tools - Claude Code, Codex, and ChatGPT all generate Markdown constantly (CLAUDE.md, plans, exports).
How to open & edit an .md file on Mac
macOS doesn't ship a Markdown viewer, so a double-click usually lands you in TextEdit and a wall of symbols. Here's the quick way to actually edit one.
1. Find the file in Finder
Locate the .md file you want to edit - a README.md from GitHub, a CLAUDE.md, or notes you exported from an AI tool. It's a plain text file, so it lives anywhere on disk.
2. Open with a Markdown editor
Double-clicking often opens TextEdit, which shows raw # and ** symbols. Instead, right-click -> Open With -> a real Markdown app. FlashType opens an entire folder of local .md files at once.
3. Edit with live rendering
Write and format visually - headings, bold, lists, links - while FlashType saves plain .md underneath. Need a hand? Claude Code and Codex are built in and edit the same files, with every change shown as a diff you accept or reject.
Ways to edit .md files on a Mac
TextEdit shows raw symbols and online viewers can't touch your local files. A native Markdown editor renders formatting, saves plain .md, and - with FlashType - puts AI agents right next to your files.
| Capability | FlashType | TextEdit | Online viewer |
|---|---|---|---|
| Renders Markdown as rich text | — | ||
| Edit and save local .md files | — | ||
| Works offline, no upload | — | ||
| Claude Code & Codex built in | — | — | |
| Review every edit as a diff | — | — | |
| Version history (via Lix) | — | — | |
| Free & open source | Some |
FAQ
What is an .md file?
An .md file is a Markdown file - a plain-text document that uses simple symbols like # for headings and **bold** for emphasis. It renders to formatted text in the right editor, but stays readable as raw text anywhere.
How do I open an .md file on a Mac?
Right-click the file in Finder, choose Open With, and pick a Markdown editor. macOS has no built-in Markdown viewer, so a dedicated app like FlashType opens any local .md file - or a whole folder - and renders the formatting properly.
Why does my .md file look like raw symbols?
Because it opened in TextEdit, which displays the plain Markdown source instead of rendering it. Open the file in a Markdown editor and the # and ** symbols turn into real headings and bold text.
What's the best way to edit Markdown on a Mac?
A native Markdown editor that renders formatting as you type while saving plain .md files. FlashType does exactly that, edits your local files directly, and adds Claude Code and Codex so AI can help - with every change reviewed as a diff.
Is FlashType free?
Yes. FlashType is free, open source under the MIT license, and runs on macOS. Issues, pull requests, and stars are welcome on GitHub.
Free & open source
Built in the open. Issues, pull requests and stars welcome.
macOS · MIT license