macOS is generous with ways to open a file, which is both a blessing and a small trap. Double-click a .md file and it usually lands in TextEdit, where it looks like someone sprinkled punctuation across your document. There is a better default, and it takes about ten seconds to set up your reading habit around it.
Quick Look gets you halfway
Select a Markdown file in Finder and press the space bar, and Quick Look gives you a fast peek. The catch is that, out of the box, it shows the raw text rather than a rendered view. It is great for confirming you grabbed the right file, less great for actually reading a long README. Treat it as a glance, not a reading experience.
TextEdit: fine for edits, not for reading
TextEdit can open any Markdown file because the file is plain text. If you only need to change a line, that is genuinely the fastest route — right-click, Open With, TextEdit, done. But because TextEdit does not interpret Markdown, you will be reading around the symbols rather than seeing the formatted result. For anything longer than a paragraph, it gets tiring quickly.
The browser is the unsung hero on macOS
The most reliable way to read Markdown on a Mac is also the least Mac-specific: open it in Safari or Chrome through a web viewer. There is no install, no Terminal, and no Homebrew rabbit hole. With mdWOW you drag the file onto the page and immediately see proper headings, drawn-out tables and highlighted code. Because the rendering happens locally in the browser tab, the file's contents stay on your machine — handy for client work or anything under an NDA.
It also solves the export problem neatly. macOS has no one-click "save this Markdown as a polished PDF" feature, but a web viewer does: open the file, choose Export, and you have a shareable PDF or an editable Word document in seconds.
For developers who live in an editor
If you already have VS Code installed, its preview shortcut renders Markdown beautifully and supports a split view for editing. That is the right tool when you are actively writing documentation. For the far more common case — you were sent a file and just want to read it — reaching for the browser keeps a quick task quick instead of turning it into a setup exercise.