Windows 11: Make a Markdown Viewer the Default for MD Files

If double-clicking README.md opens raw text, Windows is using a text editor for that extension. To read formatted headings and tables instead, choose an installed Markdown viewer as the default for .md files. This changes how Windows opens the file; it does not rewrite the document.

This guide covers file associations. For choosing a reader or downloading mdview, use the Windows Markdown viewer guide or the desktop download page.

Set the Default for .md

  1. Install the Markdown application you want to use.
  2. Open Windows Settings → Apps → Default apps.
  3. Search for .md in the file-type search field.
  4. Select the matching extension, choose your installed viewer, and confirm the choice.
  5. Double-click a local .md file in File Explorer to test it.

Microsoft documents this file-type workflow in Change default apps in Windows. Button names can vary with Windows updates.

An online viewer is a website, so choosing your browser as the default application does not automatically send local files to mdview.io. For occasional browser reading, open mdview.io and select the file directly.

Test Reading and Editing Separately

Create a small test document in your editor:

# Association test

This sentence has **bold text**.

| Item | Quantity |
| --- | ---: |
| Example | 2 |

Save it as association-test.md. Close it and reopen it by double-clicking. Check that you see a heading, bold text, and a table. Then use Open with to open the same file in your editor. A reader can be your default while an editor remains available for source changes.

Opening formatted Markdown does not guarantee diagram or math support. Test those features in the application you selected rather than assuming all readers behave identically.

If the Viewer Is Missing From the List

Right-click the document and choose Open with → Choose another app. If Windows offers Choose an app on your PC, browse to the installed application's executable. A shortcut, installer archive, or web address is not the reader executable.

Check that installation completed and that the app can open the file from its own Open menu. If it cannot, changing the association will not solve that separate problem.

If the File Still Opens as Text

Show file extensions in File Explorer and check the actual filename. notes.md.txt is a text file association even though its visible name may appear to end in .md. Rename it only after confirming that its contents are Markdown; changing an extension does not convert a Word or PDF document.

Repeat the default-app setting for .md. Related extensions such as .markdown have their own associations. Changing the default browser is a different setting and does not choose a Markdown reader.

Undo the Change

Return to Default apps, search for .md, and select your editor or previous application. Keep a test file available so you can confirm the new behavior immediately.

For private local documents, review the application's storage and network behavior separately from its file association. See reading local Markdown privately.