BlitzMD — fast Markdown viewer for Total Commander

English | Русский

---

BlitzMD is a free, open-source Markdown viewer plugin for Total Commander (a Lister plugin, WLX).

Press F3 on a .md file, or open Quick View with Ctrl+Q, and the file shows instantly, rendered the way GitHub renders it: tables, task lists, footnotes, alerts, math formulas, Mermaid diagrams, syntax-highlighted code, emoji and dark mode. BlitzMD draws the document itself with Direct2D and DirectWrite: no web browser engine, no WebView2, no .NET, nothing else to install.

Light theme	Dark theme

At a glance

What it is	Lister plugin (WLX) for Total Commander that views Markdown files
Opens	.md, .markdown, .mdown, .mkd, .mkdn, .mdwn, .mdtxt, .mdtext, .rmd
Where	Lister (F3), Quick View panel (Ctrl+Q), thumbnail view, printing
Renders	GitHub Flavored Markdown (GFM 0.29) and GitHub's extensions: alerts, footnotes, math, Mermaid, emoji, the HTML READMEs use
Total Commander	64-bit (blitzmd.wlx64) and 32-bit (blitzmd.wlx), both in one package
Windows	Windows 10 version 1703 or later, Windows 11
Engine	Native C++: md4c parser, Direct2D + DirectWrite rendering
Dependencies	None: only system libraries
Interface	English and Russian
License	MIT, free

Installation

1. Download blitzmd.zip from the latest release.
2. Open the archive in Total Commander (Enter on it). Total Commander offers to install the plugin: confirm.
3. Press F3 or Ctrl+Q on any .md file.

Manual installation: unpack the archive to any folder and add blitzmd.wlx64 (or blitzmd.wlx for 32-bit Total Commander) under Configuration → Options → Plugins → Lister plugins (WLX).

Features

GitHub Flavored Markdown

Everything in the GFM 0.29 specification: ATX and Setext headings, paragraphs, block quotes, lists (bulleted, numbered from any number, nested, tight and loose), task lists - [x], fenced and indented code blocks, tables with column alignment, strikethrough, links of every kind (inline, reference, autolinks, extended www. / https:// / e-mail autolinks), images, HTML entities, escapes and hard line breaks. Checked against the official specification tests (see Testing).

GitHub extensions

• Alerts: > [!NOTE], [!TIP], [!IMPORTANT], [!WARNING], [!CAUTION], with their Octicons icons.

• Footnotes [^1], including footnotes of several paragraphs with code and lists, with back links ↩.

• Math: $…$, $`…`$, $$…$$ and ```math blocks, typeset by TeX's rules with Cambria Math (its OpenType MATH table), as MathJax does on GitHub: fractions, roots, sub- and superscripts, limits on \sum / \int / \lim, growing delimiters \left…\right, matrices, cases / aligned, accents, over- and underbraces, \text, \mathbb / \mathcal / \mathbf, spacing, \color, \boxed. Unknown commands show as they are (in red, like MathJax); copying and searching use the TeX source.

• Mermaid diagrams (```mermaid blocks), laid out and drawn by the plugin itself, without a browser or JavaScript, in the colors of GitHub's light and dark Mermaid themes:

  • flowchart / graph: every node shape and link kind (ends, thickness, dotted, length, labels), subgraphs (with their own direction when no link crosses them), classDef / class / ::: / style / linkStyle, Markdown and HTML in labels; layered (Sugiyama) layout;
  • sequenceDiagram: participants and actors, every arrow, activations, notes, autonumber, loop / alt / opt / par / critical / break / rect, box, create / destroy;
  • classDiagram, stateDiagram, erDiagram, requirementDiagram, C4 (Context, Container, Component, Dynamic, Deployment);
  • pie, journey, gantt, timeline, mindmap, quadrantChart, xychart-beta, sankey-beta, radar-beta, treemap-beta, packet-beta, gitGraph, kanban, block-beta, architecture-beta;
  • treeView-beta, ishikawa-beta, cynefin-beta, venn-beta, wardley-beta, eventmodeling, swimlane-beta, railroad-beta (and its EBNF, ABNF and PEG forms), info.

  Diagrams zoom and open in the whole window like pictures; copying gives their source, and search highlights text on their labels. A diagram type that isn't supported, or a diagram with an error, stays a code block with a note saying why. Mermaid themes (%%{init: {theme: ...}}%%) are not applied: the colors are always GitHub's, light or dark like the document. Limits are Mermaid's: 50 000 characters and 500 links in a flowchart (2000 links in the other types).

• Emoji shortcodes :rocket: → 🚀 (the whole GitHub gemoji set, 1900+ codes), color emoji.

• Country flags 🇷🇺 🇺🇸 🇯🇵 and 🏴󠁧󠁢󠁥󠁮󠁧󠁿 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🏴󠁧󠁢󠁷󠁬󠁳󠁿: Windows' emoji font has none (it shows two letters), so BlitzMD draws them from an embedded Twemoji set (262 flags).

• Heading anchors as on GitHub (#installation, duplicates -1, -2), and links to them.

• Syntax highlighting in code blocks: about 70 languages (250+ names and extensions: C/C++, C#, Java, Kotlin, Swift, Go, Rust, JavaScript/TypeScript, Python, Ruby, PHP, Lua, SQL, Pascal/Delphi, Bash, PowerShell, batch files, HTML/XML, CSS, JSON, YAML, TOML, INI, diff, Dockerfile, Makefile, CMake, assembly, LaTeX and more), in GitHub's colors.

• Theme-specific images: #gh-dark-mode-only, <picture><source media>.

• YAML front matter (Jekyll, Hugo, Docusaurus) shows as a key–value table.

HTML used in READMEs

<div align="center">, <p align>, <h1 align>, <img width height align>, <picture>, <details> / <summary> (open on click), <kbd>, <sup>, <sub>, <mark>, <ins>, <del>, <br>, <hr>, <a name>, HTML tables (colspan), <dl>, comments. <script>, <style>, <iframe> and the like are neither run nor shown.

Images

PNG, JPEG, GIF, BMP, ICO, TIFF, WebP (through Windows Imaging Component) and SVG, including text and logos, so shields.io and GitHub Actions badges look as on GitHub. data: URIs, relative and absolute paths, spaces and non-Latin letters in file names. Animated GIFs play while they are on screen. Pictures from the internet load in the background and are cached (can be turned off); for safety, they are never requested from this computer or the local network.

Viewing

• The theme follows Total Commander's (including its dark mode, TC 10 and later), or is set to light or dark.
• Smooth scrolling, a scroll bar that marks search hits.
• Mouse selection (double click: a word, triple click: a paragraph), copying (Ctrl+C, Total Commander's menu).
• Search with Lister's dialog (F7, F3 / Shift+F3): match case, whole words, backwards; every match is highlighted, collapsed <details> open.
• Links: web links open in the browser, #anchors scroll the document, links to other .md files open in the same window (back: Backspace or Alt+←), other files open in their associated program, after a confirmation for programs and scripts. The link's address shows at the bottom of the window.
• Wide tables and long code lines (with wrapping off) scroll sideways (Shift+wheel); code blocks have a Copy button and line numbers (not copied).
• Auto-reload: when an editor saves the file, the view reads it again and stays at the same place.
• Zoom: Ctrl+wheel, Ctrl++, Ctrl+-, Ctrl+0 (remembered).
• Pictures and diagrams zoom inside their frame (Ctrl+wheel over them, drag, double click to reset) or open in the whole window.
• Percent scrolled in Lister's title; going to a percent from Total Commander's menu.
• Printing (Lister's File → Print): page breaks never split lines or table rows.
• Thumbnails for Total Commander's thumbnail view.
• Context menu: table of contents (go to any heading), copy, link or picture address, copy code block, theme, code wrapping, line numbers, text width, pictures from the internet, reload (F5), auto-reload, open in editor, settings.
• Settings window: theme, fonts, size, zoom, text width, code wrapping and line numbers, highlighting, math, emoji codes, pictures from the internet, auto-reload, smooth scrolling, GPU rendering. Changes show at once in every open viewer; OK keeps them, Cancel restores.
• Text encodings: UTF-8 (with or without BOM), UTF-16 LE/BE (with or without BOM), ANSI code pages (such as Windows-1251).

Performance

BlitzMD lays out exactly only the part of the document on screen and estimates the rest, refining it in the background, so even a document of many megabytes opens in a fraction of a second. Pictures decode in background threads, and their memory is bounded (192 MB, 96 MB in the 32-bit version): pictures not shown for a while are dropped and decoded again when they come back.

Measured on AMD Ryzen 9 5900HX, Windows 11, from Total Commander's call to the first frame on screen:

Document	Opens in	Memory
A GitHub-style README with badges and pictures (samples/gfm/02-github-readme.md)	40–45 ms	+22 MB
2.4 MB of Markdown, 18 000 paragraphs (samples/gfm/09-large-document.md)	0.12–0.15 s	+51 MB

The time varies from run to run with the processor's state; the table gives the usual range.

Keyboard and mouse

Key / action	What it does
↑ ↓, PgUp PgDn, Space / Shift+Space, Home End	Scroll
Wheel / Shift+wheel	Scroll / scroll a wide table or code block sideways
Ctrl+wheel, Ctrl++, Ctrl+-, Ctrl+0	Zoom
Ctrl+wheel over a picture, drag, double click	Zoom the picture in its frame, move it, reset
⛶ button on a picture or diagram	Whole window: wheel zooms, + - 0, arrows; Esc goes back
Ctrl+A, Ctrl+C	Select all, copy
Click a link	Open the link / go to the anchor / open the .md file
Backspace, Alt+←	Back after following a link
Click a <summary>	Open / close its <details>
F5	Read the file again
F7, F3, Shift+F3	Search (Lister's dialog)
N, P, Esc, 1–7 …	Lister's own keys (handled by Total Commander)

Settings

Change them in the settings window (context menu → Settings…), some straight from the context menu. They are stored in blitzmd.ini next to wincmd.ini (section [blitzmd]); the file is created on the first change, and every key is optional.

Key	Default	Meaning
Theme	0	0: as Total Commander (or Windows), 1: light, 2: dark
Font	Segoe UI	Text font
MonoFont	(auto)	Monospaced font; Cascadia Mono if installed, else Consolas
FontSize	16	Base font size (as GitHub's 16 px)
Zoom	100	Zoom in percent (30–400)
MaxWidth	900	Maximum text width; 0: the whole window
WrapCode	-1	Wrap long code lines: -1 as Lister's Wrap text, 0 / 1 off / on
LineNumbers	1	Line numbers in code blocks of two lines or more
AutoReload	1	Read the file again when it changes on disk
RemoteImages	1	Load pictures from the internet (http/https)
SmoothScroll	1	Smooth scrolling
EmojiShortcodes	1	Replace :code: with emoji
Math	1	Math formulas $…$
Mermaid	1	Mermaid diagrams (0: show their source)
SyntaxHighlight	1	Syntax highlighting
HardwareRendering	0	1: draw with the GPU (for very large windows, 4K); software Direct2D opens faster and uses less memory

FAQ

How do I view Markdown files in Total Commander? Install BlitzMD (see Installation), then press F3 on a .md file, or Ctrl+Q to show it in the other panel.

Does BlitzMD need a browser, Internet Explorer, WebView2 or .NET? No. It parses Markdown with md4c and draws the document with Windows' own Direct2D and DirectWrite. The plugin is a single DLL with nothing else to install.

Does it show Markdown like GitHub does? Yes, that is its aim: GitHub's typography and colors (light and dark), GFM tables and task lists, alerts, footnotes, math, Mermaid diagrams, emoji, and the HTML that READMEs use.

Does it work with 32-bit Total Commander? Yes. The package contains blitzmd.wlx (32-bit) and blitzmd.wlx64 (64-bit); Total Commander installs the right one.

Does it support dark mode? Yes. By default the theme follows Total Commander's dark mode (or Windows'); it can also be set to light or dark.

Can it render Mermaid diagrams and LaTeX math? Yes, both are drawn by the plugin itself, without JavaScript: 30 Mermaid diagram types, and TeX math typeset with Cambria Math.

Is it safe to open untrusted Markdown files? Scripts in HTML are never run. Links to programs or scripts, and links to other computers' shares, open only after a confirmation. Pictures from the internet are never requested from this computer or the local network, and their download can be turned off.

Does it edit Markdown? No, BlitzMD is a viewer. Open in editor in its context menu opens the file in the program Windows uses to edit .md files, and F4 in Total Commander opens it in Total Commander's editor.

Is BlitzMD free? Yes, it is open source under the MIT license.

Building from source

Visual Studio 2022 or 2026 with the C++ workload, and CMake (comes with Visual Studio). Everything else is in the repository (md4c in third_party); no network access is needed to build.

# x64 Release -> out\build\x64-release\blitzmd.wlx64
powershell -File scripts\build.ps1

# x64 + x86, packaged as dist\blitzmd.zip (installs from Total Commander)
powershell -File scripts\build.ps1 -Arch all -Package

The project folder can also be opened in Visual Studio (CMake presets x64-release, x86-release).

Testing

The whole test suite (CI runs the same):

powershell -File scripts\test.ps1                                          # x64
powershell -File scripts\test.ps1 -Build out\build\x86-release -Quick     # x86, less fuzzing

What test.ps1 checks:

• Specifications: GFM 0.29, CommonMark 0.31.2, the GFM tables, strikethrough and autolinks extensions, and BlitzMD's own cases (tests/spec/mdview-extensions.txt: front matter, HTML lists, footnotes and more).
• Parts of the renderer: syntax highlighting (1.4 million checks and fuzzing), the emoji table, flag emoji, collapsed <details>, math, every Mermaid diagram of the samples (with hostile input and fuzzing), paragraphs of tens of thousands of formatted pieces.
• Every sample of samples/gfm/ rendered at 320 and 900 pixels wide.
• The plugin DLL, driven the way Total Commander drives it: three samples with thumbnails, auto-reload, the settings window, zooming pictures, pictures from a server that doesn't answer, search, a change of the Windows theme, the printer chosen in Total Commander, freeing the DLL, the first paint, closing inside a modal loop, data: URIs, text encodings, paths longer than 260 characters.
• Fuzzing: 400 random documents (100 with -Quick) through parsing, layout and drawing.

Specification results: 614 of the 672 GFM 0.29 examples match the reference output. Of the other 58, 53 are about raw HTML, which BlitzMD interprets on purpose instead of showing it as text, 3 are cases where the md4c parser differs from the specification, and 2 are disabled in the specification itself. CommonMark 0.31.2: 596 of 652 match, with the same 53 raw HTML and 3 md4c cases. No example fails.

Before a merge, scripts\verify.ps1 builds and tests the working tree the way CI does, plus an AddressSanitizer build (-DMDVIEW_ASAN=ON): x64 with the full test.ps1, x86 with -Quick, and the fuzzer and the modal loop test under ASan. -Skip asan leaves the ASan build out, -Asan { … } runs more commands under it; the logs go to out\verify\.

Single checks use mdview_test.exe, built with the plugin:

$t = "out\build\x64-release\mdview_test.exe"
$dll = "out\build\x64-release\blitzmd.wlx64"
& $t spec tests\spec\gfm-spec.txt [-v] [-n 42]      # a specification file, or one example of it
& $t render samples\gfm\02-github-readme.md out.png --width 900 [--dark] [--zoom 1.5] [--lines]
& $t pages  samples\gfm\05-tables.md page           # pages as printed
& $t bench  samples\gfm\09-large-document.md        # parsing and layout times
& $t dump   README.md                               # the parsed document as HTML
& $t text   README.md                               # the text Ctrl+A, Ctrl+C copies
& $t fuzz   2000                                    # random documents: parse + layout + drawing
& $t mermaid samples\gfm\20-mermaid-flowchart.md    # diagrams: parsing, layout, fuzzing
& $t mmd diagram.mmd out.png [--dark]               # one Mermaid diagram to PNG
& $t math samples\gfm\18-math.md                    # math: TeX parsing, typesetting, fuzzing
& $t tex "\frac{a}{b}"                              # one formula's parsed tree
& $t plugin $dll README.md shot.png "search text" [--dark]   # the DLL, as TC drives it
& $t settings $dll README.md out\tmp\set\s          # settings window
& $t zoom $dll tests\zoom.md out\tmp\zoom\z         # zooming pictures
# <dll> <out-dir>: reload, search, remote, theme, unload, firstpaint, modal
& $t reload $dll out\tmp\reload                     # auto-reload
& $t inputs all                                     # data: URIs, text encodings, SVG
& $t longpath out\tmp\longpath                      # a picture at a path over 260 characters
& $t printer dialog                                 # the printer chosen in Total Commander
& $t heavy 5000                                     # huge paragraphs: first screen within 5 s
out\build\x64-release\highlight_test.exe -q         # syntax highlighting
out\build\x64-release\emoji_test.exe                # emoji table

scripts\screenshots.ps1 takes the README screenshots again from the documents in docs/screenshots/. samples/gfm/ holds documents for checking by eye: a tour of the whole specification, a GitHub-style README, alerts, footnotes and math, 45+ programming languages, tables, lists, typography in 15+ languages (right-to-left included), edge cases and a 2.4 MB document.

Continuous integration and releases

GitHub Actions (.github/workflows/ci.yml) builds x64 and x86 on every push and pull request, runs scripts\test.ps1 and attaches blitzmd.zip to the run.

A release:

1. Set the version in CMakeLists.txt (project(blitzmd VERSION x.y.z ...)); it goes into the DLL's version resource and into pluginst.inf when packaging.
2. Commit, tag and push the tag: git tag vx.y.z, git push origin vx.y.z.
3. CI checks that the tag matches the version, builds, runs the tests and publishes a GitHub Release with blitzmd.zip, which Total Commander installs by itself.

Architecture

src/plugin.cpp        WLX exports: ListLoad(W), ListLoadNext(W), ListSearchText(W),
                      ListSendCommand, ListPrint(W), ListGetPreviewBitmap(W), ...
src/core/parser.*     md4c → block tree; GitHub's HTML subset, emoji, anchors, footnotes
src/core/html.*       HTML tokenizer
src/core/texmath.*    TeX formulas into atom trees
src/core/mathlayout.* math typesetting by TeX's rules with the OpenType MATH table (Cambria Math)
src/core/flags.*      flag emoji from the embedded Twemoji set (src/twemoji-flags.bin, made by
                      scripts/gen_flags.py)
src/core/highlight.*  syntax highlighting
src/core/layout.*     layout: DirectWrite, exact near the view, estimated elsewhere
src/core/render.*     Direct2D drawing (GitHub Primer themes)
src/core/images.*     WIC, SVG, background http(s) downloads with a cache
src/core/zoom.*       zooming pictures and diagrams in their frame and in the whole window
src/core/mermaid*     Mermaid diagrams: parsers (a file per type), scene building
src/core/graphlayout.* layered graph layout (Sugiyama) with clusters
src/core/diagram.*    diagram scene: shapes, paths, DirectWrite text; drawing by theme
src/core/viewer.*     the Lister window: scrolling, selection, links, search, menus
src/core/settings*    settings (blitzmd.ini) and the settings window
src/core/print.*      printing
third_party/md4c      md4c 0.6.0 with a few GitHub compatibility changes

License

MIT (see LICENSE). Uses md4c (MIT), gemoji data (MIT) and Octicons icons (MIT).

Flag images: Twemoji © Twitter, Inc. and other contributors, CC-BY 4.0; coordinates in the embedded set are rounded to hundredths.