mdevs — Edit Markdown right in the preview

Write Markdown in Visual Studio the way you read it. mdevs turns .md files into a page you edit directly: headings, lists, tables, and images take shape as you type. No source pane, no preview pane, no switching back and forth — and the file you save is still plain Markdown.

日本語の説明は README.ja.md を参照してください。

mdevs editing a Markdown document in GitHub style, with the outline, a table, a pasted image, and the context menu

Why mdevs

One view, what you see is what you save — Type ## , **bold**, - , or |a|b| and the formatting appears as soon as you finish the mark.
Clean diffs — Only the blocks you actually edit are rewritten. Everything else keeps its original spacing and line breaks, so opening and saving a file does not fill your Git diff with noise.
Tables that are easy to work with — Tab between cells, add rows with Ctrl+Enter, and insert or delete rows and columns from the right-click menu.
Paste screenshots — Ctrl+V pastes an image; when you save, it is stored next to your file and linked with a relative path.
Works with Excel and Word — Paste an Excel range to get a Markdown table. "Copy for Excel" sends headings, lists, and tables back to Excel one cell per line; normal copy pastes into Word with formatting.
Still Visual Studio — Save, undo, the unsaved-changes marker, Find and Replace, Find in Files, and your shortcuts behave as usual. An outline next to the document lets you jump through long documents.
Two looks, light or dark — GitHub style or VS Code preview style, following your Visual Studio color theme. English and Japanese UI.

Choose your style

Prefer the look of the Visual Studio Code Markdown preview? Switch Display Style in the options. The editing features are the same in both styles.

mdevs in VS Code style

Get started

In Visual Studio, open Extensions > Manage Extensions, search for "mdevs", and install it.
Open any .md or .markdown file from Solution Explorer or elsewhere. It opens in mdevs.
Write, then save with Ctrl+S.

Requires Visual Studio 2022 (version 17.14 or later) or Visual Studio 2026 (64-bit). The editor uses the Microsoft Edge WebView2 Runtime (included with Windows 11).

To edit a file as plain text, right-click the file in Solution Explorer → Open With..., and choose Source Code (Text) Editor (click Set as Default in the same dialog to change the default way of opening).

Full help is built in. Right-click in the editor → Open Help opens a complete, read-only guide in the language of the editor.

Everything at your right click

Right-click in the document for the commands you use most:

Back to Top
Cut, Copy, Copy for Excel, Paste, Paste without Formatting
Bold, Italic, Underline, Strikethrough, Inline Code, Highlight
Make Link… and Insert Table…
On a link: Open Link, Copy URL, Edit Link…, and Remove Link
Switch to Source Mode and Open Help

Commands that already apply to the selection are checked (✓). Right-click a table cell for table commands, and a paragraph or heading to change the heading level.

Writing at a glance

To get	Type (or use)
Heading	`#` to `######` at the start of a line
Quote	`>` at the start of a line
Bold / Italic	`text` / `text`, or `Ctrl+B` / `Ctrl+I`
Underline	Select text and press `Ctrl+U`
Strikethrough / Highlight	`~~text~~` (`Alt+Shift+5`) / `==text==`
Inline code	`text`
Bulleted / numbered list	`-` / `1.` at the start of a line
Check box	`[ ]` or `[x]` at the start of a list item
Code block	``` (optionally with a language) and Enter
Horizontal rule	`---` and Enter
Table	`\\|Header 1\\|Header 2\\|` and Enter, or Insert Table…
Link	`[text](URL)`, or select text → Make Link…

Lists: Enter adds an item, Tab / Shift+Tab indents / outdents, Shift+Enter breaks the line inside an item, and Enter on an empty item leaves the list. Tables: Tab / Shift+Tab move between cells (Tab in the last cell adds a row), Enter moves to the cell below, Shift+Enter breaks the line inside a cell, Ctrl+Enter inserts a row below.

Find, navigate, and view the source

Find and replace — Uses the Visual Studio search.

Operation Keys

Open the Find and Replace window Ctrl+F / Ctrl+H

Find next / previous F3 / Shift+F3

"Replace All" works on the Markdown source (so **, link URLs, and so on are also replaced).
Find in Files — Ctrl+Shift+F / Ctrl+Shift+H work as usual, and replacements show up immediately in open mdevs editors. Double-click a line in "Find Results" to open the file and show the match.
Outline — The left side of the editor lists the headings of the current document. Click one to jump to it. The Hide Outline / Show Outline button in the status bar shows or hides it.
Source mode — Show Source in the status bar at the bottom of the editor (or right-click → Switch to Source Mode) shows the raw Markdown; Show Markdown switches back.
Zoom — Ctrl++, Ctrl+-, Ctrl+0, or Ctrl+mouse wheel.

Images and links

Paste an image from the clipboard with Ctrl+V. It is kept in a temporary folder until you save; when you save, it is moved into a <file name>.images folder next to the file (for example clipboard_image_1.png), and a relative link is written into the document. With Save As to another folder, images with relative paths are copied so that they stay at the same relative location.

Links open with a single click: web links in your browser, #heading links inside the document, and relative links to other Markdown files in a new Visual Studio tab.

Keyboard

Keys for editing (typing, Ctrl+B / Ctrl+I / Ctrl+U, Alt+Shift+5, undo / redo, copy / paste, zoom, etc.) are handled by the editor. Other keys (Ctrl+S, Ctrl+Tab, F5, Ctrl+Shift+B, etc.) work as Visual Studio shortcuts.

Settings

mdevs settings in the Visual Studio options

Open Tools > Options > mdevs > Display. Changes apply immediately to all open editors.

Setting	Values
Language	Auto (default; follows the Visual Studio display language: Japanese if it is Japanese, otherwise English) / Japanese / English
Display Style	GitHub style (default) / VS Code style
Text Color	Sharp (default) / Easy on the eyes
Text Width	Readable width (max 884px, default) / Fit to the editor width
Line Breaks in Paragraphs	Do not break until a blank line (default) / Break lines as in the source. Display only; the saved file is the same.

The Language setting applies to the editor screen, messages, dialogs, and the help. The options page itself is shown by Visual Studio, so its labels are written in both English and Japanese. Light and dark appearance follows your Visual Studio color theme.

Known limitations

Ctrl+F / Ctrl+H open the Find and Replace window. The small Quick Find box is for text editors and cannot be used in mdevs.
With "Copy for Excel", images may be shown over the text of the row below in Excel.

Install from a VSIX file

Close all instances of Visual Studio.
Double-click the mdevs.vsix file. The VSIX Installer opens; follow the instructions on the screen.

To uninstall, choose mdevs in Visual Studio under Extensions > Manage Extensions.

Development

Folder structure

Path	Contents
`mdevs.slnx`	Solution
`mdevs/mdevsPackage.cs`	Entry point of the extension (registers the editor and the options page)
`mdevs/MarkdownEditorFactory.cs`	Editor factory that creates the editor pane when a `.md` or `.markdown` file is opened
`mdevs/MarkdownEditorPane.cs`	Editor pane (loading and saving as a Visual Studio document, find, detecting changes by other apps, etc.)
`mdevs/MarkdownWebHost.cs`	Contents of the editor pane (shows the screen with WebView2; reads and writes files, pastes images, opens links, etc.)
`mdevs/KeyboardRouter.cs`	Routes key input between Visual Studio shortcuts and the editor screen
`mdevs/NavigationCapture.cs`	Shows the match when a file is opened from "Find Results"
`mdevs/MdevsOptionsPage.cs`, `MdevsSettings.cs`, `registration.json`	Settings under Tools > Options
`mdevs/UiThread.cs`, `Log.cs`	Work on the UI thread, and the log (the "mdevs" pane of the Output window)
`mdevs/dialog/`	The "Insert Table…", "Make Link…", and "Edit Link…" dialogs
`mdevs/help/HELP.en.md`, `HELP.md`	Help in English / Japanese (opened read-only from the right-click menu → Open Help. The one for the language of the editor is opened)
`mdevs/web/`	Editor screen (HTML, JavaScript, CSS). `js/i18n.js` holds the English text of the screen (the Japanese text is the key)
`mdevs/Text.cs`	English text of the messages and dialogs shown by the extension (the Japanese text is the key)
`mdevs/images/mde.png`	Icon of the extension
`mdevs/LICENSE.txt`	License included in the VSIX (the mdevs MIT License and the WebView2 license)
`mdevs/source.extension.vsixmanifest`	Information about the extension (name, version, publisher, supported Visual Studio, etc.)
`README.md`, `README.ja.md`	This file (English) / Japanese version
`images/readme/`	Screenshots used in the README (the English README loads them from GitHub, so push them before publishing)

Trying it out

Install the "Visual Studio extension development" workload in Visual Studio 2026.
Open mdevs.slnx and build.
Press F5 to start Visual Studio with mdevs loaded (the experimental instance), and open a .md file.
The log is shown under View > Output by choosing "mdevs" in "Show output from". For the editor screen itself, press F12 in the editor to open the developer tools.

Building the VSIX

Build with the "Release" configuration to create mdevs\bin\Release\net472\mdevs.vsix. This is the file to distribute. Change the version with Version in source.extension.vsixmanifest (the VSIX version) and Version in mdevs.csproj (the DLL version).

License

MIT License (LICENSE.txt). The license of WebView2, which mdevs uses, is in mdevs\LICENSE.txt.

mdevs - Inline Markdown Editor for Visual Studio

mde-tools