MDFlash

A fast WYSIWYG Markdown editor for Windows, written in C.
Write Markdown and see it formatted as you type: no split preview, no clutter.

_{Windows 10 and 11 (64-bit) · 5 MB installer · no administrator rights needed · all releases}

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Why MDFlash

• It feels like Typora. Headings, lists, tables, math and diagrams take shape where you type them. Press Ctrl+U whenever you want the raw Markdown.
• It is small and native. A 260 KB C program drives Microsoft Edge's WebView2 engine, which Windows already ships. No 150 MB Electron bundle.
• It respects your files. Opening a document never rewrites it. Line endings, encoding, front matter, [[wiki links]] and image descriptions are preserved when you save.
• It goes further. Tabs, version history, folder-wide search, an offline writing assistant and native Word export are built in.

Features

Writing

• Seamless live editing (WYSIWYG) and a source mode with syntax highlighting
• GitHub Flavored Markdown: tables with alignment, task lists, strikethrough, footnotes, autolinks
• Math with KaTeX ($...$ and $$...$$) and diagrams with Mermaid
• Code blocks with syntax highlighting for more than 100 languages
• ==highlight== and Obsidian-style [[wiki links]]: Ctrl+click opens or creates the note
• YAML front matter kept intact and editable in its own box
• Press / on an empty line for a menu of headings, lists, tables, math, diagrams, images and footnotes
• Paste or drop images: they are copied next to the document and linked with relative paths

Organizing

• Tabs, session restore and automatic recovery of unsaved text after a crash
• Version history: a copy on every save, with a line-by-line diff and one-click restore
• Sidebar with document outline, folder tree (new, rename, duplicate, move to Recycle Bin) and full-text search across a whole folder
• Quick open (Ctrl+P), command palette (Ctrl+Shift+A), find and replace with regular expressions
• Changes made by other programs are detected and reloaded

Focus

• Focus mode (F8) dims everything except the paragraph you are writing
• Typewriter mode (F9) keeps the current line in the middle of the screen
• Live word, character and reading-time count, with an optional word goal

Export and import

• PDF, HTML (styled or plain) and Word (.docx) with no extra software
• ODT, RTF, EPUB, LaTeX, reStructuredText and MediaWiki through Pandoc when installed
• Copy as Markdown or as formatted HTML for e-mail and Word
• Import Word, HTML and CSV (more formats with Pandoc)

Offline writing assistant

• With Ollama running locally, press Ctrl+J to fix, improve, shorten, expand, summarize, translate or rewrite the selected text
• Answers stream in as they are written; replace the selection, insert below or copy
• Your text never leaves your computer

Look and feel

• Six themes (GitHub, Paper, Sepia, Academic, Night, Nord) plus your own CSS themes
• Follows the Windows light and dark setting; the native menu bar turns dark too
• Interface in English, Italian, Spanish, French, German, Japanese, Korean, Chinese and Russian, picked automatically from Windows (View > Language to change it)

Screenshots

Night theme with math and diagrams	Source mode (Nord theme)	Japanese interface (Paper theme)

Install

1. Download MDFlash-Setup-2.0.0.exe with the button above.
2. Run it. The setup speaks the same nine languages, installs for the current user without administrator rights (or for all users, if you choose), and can make MDFlash the program that opens .md files.

Requirements: Windows 10 or 11, 64-bit, with Microsoft Edge WebView2 Runtime (already part of Windows 11; the setup points you to it if it is missing).

Portable use: copy the program folder anywhere (for example a USB stick) and create an empty file named portable next to MDFlash.exe. Settings, version history and caches will stay in a data folder beside it.

Windows may show an "unknown publisher" notice because the executable is not code-signed yet. Choose More info > Run anyway.

Keyboard shortcuts

Action	Keys
Quick open / command palette	Ctrl+P / Ctrl+Shift+A
Source mode	Ctrl+U
Focus / typewriter mode	F8 / F9
Find / replace / search in folder	Ctrl+F / Ctrl+H / Ctrl+Shift+F
Sidebar	Ctrl+Shift+L
Writing assistant	Ctrl+J
Heading 1 to 6, paragraph	Ctrl+1 … Ctrl+6, Ctrl+0
Bulleted, numbered, task list	Ctrl+Shift+8, 7, 9
Bold, italic, inline code, link	Ctrl+B, Ctrl+I, Ctrl+E, Ctrl+K
Table, code block, math block	Ctrl+T, Ctrl+Shift+K, Ctrl+Shift+M
Next / previous tab	Ctrl+Tab / Ctrl+Shift+Tab

The full list is in Help > Keyboard Shortcuts, and F1 opens a Markdown quick guide in your language.

Custom themes

Themes > Open Themes Folder opens %APPDATA%\MDFlash\themes. Any .css file placed there appears in the Themes menu. A theme overrides a few CSS variables (--bg, --text, --accent, --font-body…); add the comment /* mdflash: dark */ for a dark theme. An annotated example is created in the folder.

How it is built

Part	Technology	Where
Window, native menu, file I/O with encoding detection, dialogs, PDF and Word export, clipboard, Pandoc and Ollama calls, file association, single instance	C (Win32 API and COM), about 3,300 lines	src/
Rendering engine	Microsoft Edge WebView2	sdk/webview2/
Editing surface	Milkdown Crepe (ProseMirror), CodeMirror 6, KaTeX, Mermaid, bundled with esbuild	web/
Installer	Inno Setup 6	installer/

The C host and the page exchange JSON messages (src/bridge.c, web/src/host.js). WebView2 event handlers are written as plain C COM objects, without the C++ helper library.

Build from source

Requirements: LLVM-MinGW (clang and windres on the PATH), Node.js 20 or later, and Inno Setup 6 for the installer.

build.cmd              :: build\MDFlash.exe and build\app\
build.cmd installer    :: also dist\MDFlash-Setup-2.0.0.exe

Tests

The end-to-end test drives the real executable through the WebView2 debugging port with Playwright:

set WEBVIEW2_ADDITIONAL_BROWSER_ARGUMENTS=--remote-debugging-port=9333
start build\MDFlash.exe
node tools\e2e.mjs

It opens, edits and saves real files, checks line endings and front matter, version history, external changes, source mode, search, PDF, HTML and Word export, wiki links and single-instance handling. node tools\i18n-keys.mjs checks that all nine languages are complete.

Support

MDFlash is free and open source. If it is useful to you, you can support its development:

Bug reports and ideas are welcome in Issues.

Credits

Made by Elecktra Studio, author ShinRalexis.

Built on Milkdown, ProseMirror, CodeMirror, KaTeX, Mermaid, cJSON and Microsoft WebView2.

License

MIT © 2026 Elecktra Studio, ShinRalexis. Bundled components keep their own licenses.