Claude made a .md file. Here is how to open it.

You asked Claude for a project plan, a spec, some research or a set of meeting notes. It gave you a file. You downloaded it, double-clicked it, and instead of a document you got something like this:

## Phase 1 — Discovery

**Goal:** confirm the problem is worth solving.

- [ ] 5 customer interviews
- [ ] Review support tickets from Q3

| Risk | Likelihood |
| ---- | ---------- |
| Scope creep | High |

Nothing is broken and nothing is missing. That is the whole document — you are just seeing the plumbing. Two minutes of setup and it will look like the document it already is.

What a .md file actually is

.md is Markdown: plain text with a few punctuation conventions that mean "this is a heading", "this is bold", "this is a list". ## is a heading. **like this** is bold. A line starting with - is a bullet, and - [ ] is a checkbox. Pipes draw a table.

It is a real document format, just one that has to be rendered by something before it looks like a document — the same way a web page is HTML underneath. GitHub renders Markdown. Notion renders it. Claude's own interface renders it, which is why the plan looked fine in the chat and looks like code on your desk.

Why Claude writes Markdown instead of Word

Markdown is the native document format of AI tools, for a few reasons that have nothing to do with you: it is plain text, so a model can write it, edit one line of it, and diff it; it carries structure without any of the binary machinery of .docx; and it opens on every operating system and in every version-control system without a licence.

Claude Code, Codex, Cursor and the rest go further — they keep working documents in Markdown next to your project: a PLAN.md they tick off as they go, a CLAUDE.md of standing instructions, a README.md for whoever arrives next. If you are wondering which of those files is worth reading, we wrote a plain-English tour of the ones AI tools create.

The fastest way to read one: press Space

macOS has a built-in preview — Quick Look. Select a file in Finder, press Space, and a PDF, an image, a spreadsheet or a Keynote deck appears instantly. Press Space again and it is gone.

On a .md file it shows you the raw text, because macOS ships no Markdown renderer. Installing a Markdown app with a Quick Look extension fixes that for every Markdown file on the machine, permanently: after it, Space on PLAN.md shows the rendered plan, headings and tables and all. No app to open, nothing to configure per file.

That is the setup worth doing first, because it costs one install and changes every future file. The long version is in Markdown Quick Look on macOS, and if you have installed something and Space still shows asterisks, the checklist for that.

The second thing: make double-click do the right thing

Quick Look is for glancing. For actually reading a fourteen-page spec you want a window you can scroll, search and leave open. By default macOS hands .md to whatever text-capable app ranks highest — TextEdit on a normal Mac, Xcode on a developer's. Both show source.

To point every Markdown file at a reader instead:

1. Select any .md file in Finder.
2. Press ⌘I for Get Info.
3. Open Open with and choose your Markdown app.
4. Click Change All… and confirm. This is the step people skip, and without it you have changed one file rather than the file type.

You do not need a code editor for any of this. If someone has already told you to install VS Code just to read a document, see opening and editing Markdown without VS Code.

Getting it out to everyone else

Most of the time the file is not the destination. The plan has to go in the deck, the spec has to go in Notion, the summary has to go to someone who will never install anything. Three moves cover almost all of it:

• Into Notion, Google Docs, Confluence or an email. Copy the document as rich text from a Markdown app and paste. Headings stay headings, tables stay tables, links stay links. Copying the raw source instead is what produces a wall of asterisks in someone's inbox. (Notion and Google Docs will also import a .md file directly, which is better for a long document.)
• As a PDF. Open the file rendered and press ⌘P → Save as PDF. This is the safe format for anyone outside the company, and the one that survives being forwarded.
• As a Word file. Right if the recipient has to edit or comment. Some Markdown apps export .docx directly; otherwise paste the rich text into Word.

A note on files that keep changing

If Claude Code is running while you read, the file underneath you is a moving target — agents save by writing a new file and renaming it over the old one, which is enough to strand most preview windows on a version that no longer exists. If your preview looks stale, that is why, and it is testable.

nicemd

nicemd is a small Mac app built for exactly this: double-click a .md file and read it as a document, with an outline down the side and live reload while an agent rewrites it underneath. It installs the Quick Look extension, so Space in Finder renders Markdown from then on, and it can make itself the default for .md from its own settings.

Reading, Quick Look, Save as PDF and Copy as HTML — the one that pastes as formatted text into Notion, Docs or an email — are free; edit mode, split view and export to HTML and Word are a one-time unlock.