FastMD

English · Русский

A lightning-fast Markdown reader for Windows. About 65 ms pass between launching it and a rendered document on screen. An untuned empty Win32 window takes longer than that to open.

C++20, Win32, DirectWrite, md4c. The interface speaks English and Russian; the rest of the documentation is in Russian.

Download

FastMD 1.3.1 — latest release:

1. FastMD-Setup.exe — a per-user install, no administrator rights: a Start menu shortcut, the .md association, a preview pane in Explorer. Uninstalls through Settings → Apps.
2. Or FastMD-1.3.1-win-x64.zip — unpack it anywhere and run FastMD.exe; to make .md files open on a double click, pick "Open .md files with FastMD…" from the context menu and confirm the choice in Settings.

The exe is not signed yet, so on the first run Windows SmartScreen may warn you: "More info" → "Run anyway". Code signing is waiting on a certificate (task 5.5).

Why it is this fast

The stack was picked by measurement: 12 prototypes, 47 variants, one harness and one protocol. The details are in REPORT.md. Below is the time from process start to a rendered document (medium.md, 53 KB, median):

What is opened	ms
The FastMD prototype: C++, Win32, DirectWrite, first frame on the CPU	59
An empty, untuned Win32 window	78
Qt 6 Widgets	149
WinUI 3 (C#, NativeAOT)	324
WebView2 / Tauri	447–630
Electron (the Typora, Obsidian class)	753–903
VS Code, the window alone	1,138

FastMD itself in the control run: 66.7 ms against 79.2 ms for the empty window under the same conditions. Everything added since then works off the critical path of the first frame.

The techniques that matter:

• the first frame is drawn on the CPU (DirectWrite → GDI DIB), because a GPU device created before the first frame would have cost +150–250 ms;
• only the first screen is laid out at first, the rest is done in the background after the first frame;
• one small exe (~1.4 MB with edit mode), static CRT, no runtimes;
• when the window is first shown, IME initialization on the UI thread and the open animation are both off; the search box, which needs IME, lives on a thread of its own, and the text services that switch the keyboard layout start right after the first frame.

When a launch takes longer than usual

Now and then — usually the first time after an install or an update — the window appears noticeably later than it normally does. That is not FastMD: the antivirus is scanning an exe it has not seen before, and it does so inside CreateProcessW, before the program's first line of code runs at all. The launches after it are quick again, because the verdict is cached.

To be rid of it entirely, add the program's folder to the antivirus exclusions. For Microsoft Defender: Windows Security → Virus & threat protection → Virus & threat protection settings → Manage settings → Exclusions → Add or remove exclusions → Add an exclusion → Folder, and point it at

%LOCALAPPDATA%\Programs\FastMD

(or, if you unpacked the zip, at the folder you unpacked it into). The exclusion lifts scanning from that folder only; everything else on the machine stays protected exactly as before.

Features

• Markup: CommonMark and GFM (tables, task lists, strikethrough, autolinks), GitHub Alerts, footnotes, YAML front matter as a table, emoji shortcodes, syntax highlighting for 55 languages, color emoji, CJK.

• Like GitHub: a subset of HTML (alignment, <details>, <picture>, tables, <kbd>, inline images), SVG and badges, images from the network with an on-disk cache.

• Math and diagrams: $…$ and $$…$$ are genuinely typeset (RaTeX, KaTeX-compatible), and a ```mermaid block is drawn as a diagram — graph / flowchart is laid out by our own layout engine, the other kinds are drawn by the library. A diagram takes the full width of the window, and where even that is not enough it scrolls sideways instead of shrinking into illegibility. Both libraries load only for a document that needs them.

• Reading:

  • a table of contents that follows the current section (Ctrl+Shift+O);
  • wide code and tables scroll sideways (Shift+wheel, touchpad);
  • column width from narrow to full (Ctrl+Alt+← / →);
  • the Sitka book font, and a text size;
  • GitHub light and dark themes, Mica, the Windows high-contrast theme.

• Working with text:

  • selection by mouse and by keyboard (Shift+arrows, by word, to the ends of the line and of the document);
  • copying with formatting (HTML and RTF) and as Markdown source (Ctrl+Shift+C);
  • dragging text, links and images into other applications;
  • printing and PDF export (Ctrl+P, Ctrl+Shift+P) — as text, not as a picture;
  • task list boxes tick with a click, in the file itself (- [ ] ↔ - [x]): only the character between the brackets changes, and only while the file on disk is exactly what is on screen. Outside edit mode this is the one time FastMD writes to a document.

• Editing in place: a double click puts a caret into the rendered page, a toolbar slides down from the top, and the edits are saved into the file as you type — see Editing.

• Search: Ctrl+F, case sensitivity, whole words, match marks on the scrollbar, IME input.

• Memory:

  • a document opens at the place where you closed it;
  • the window opens where it was;
  • with no file given it shows recent documents with search by name; the same list is in the Jump List.

• Navigation: GitHub-style heading anchors, relative .md links with back / forward history, Tab through links, link and image context menus.

• In Explorer: a .md preview pane on the same engine (10–19 ms against 0.6–1.4 s for PowerToys) and page thumbnails in place of a file icon.

• Environment:

  • a per-user installer, no administrator rights, and an update check once a day (which can be turned off);
  • live reload when the file changes;
  • "Open in editor" with an editor of your choice;
  • a settings window, interface in Russian and English;
  • screen reader support: the document, and movement by word, line, paragraph and heading.

  A 3.7 MB document shows its first screen in the same ~66 ms.

Editing

FastMD edits a document where it shows it: the page keeps its look, with no switch to a text editor.

• In and out. Double-click the text, press F2, click the pencil at the top right, or pick "Edit here" in the context menu: a caret appears there and a toolbar slides down from the top. Esc (once whatever is open is closed), F2 or the ✕ at the right end of the toolbar leave edit mode.
• The toolbar: undo and redo, the paragraph style (text, headings 1–6), bold, italic, strikethrough, inline code, link, bulleted, numbered and task lists, quote, code block, table, formula, diagram, image, horizontal rule, and the save status. In a narrow window the rest goes under "…". Markdown typed at the start of a line works as well: # , - , 1. , > , ```, ---.
• Formulas, diagrams, pictures, HTML blocks and front matter are edited as source: a click opens a small editor under the object, and the page redraws it as you type. Ctrl+Enter keeps the change, Esc takes it back.
• Keys: Ctrl+B / Ctrl+I, Ctrl+K a link, Ctrl+1…6 headings, Ctrl+Shift+7 / 8 / 9 lists, Ctrl+Shift+Q a quote, Ctrl+Shift+K a code block, Ctrl+T a table, Ctrl+M a formula, Ctrl+Enter a new paragraph, Ctrl+Z / Ctrl+Y undo and redo, Ctrl+S save. The full list is in app/README.md.
• Saving. Edits are saved by themselves 0.8 s after the last one (2–5 s for files over a million characters), and always when you leave edit mode, the document or the program. Autosave is turned off in Settings → "Autosave edits": then Ctrl+S saves, and so does leaving edit mode. The undo history lasts while the document is open, across saves and across leaving and re-entering edit mode.
• What is written. Only the part of the file that changed is rewritten, in place: the encoding (UTF-8 with or without a BOM, UTF-16 LE, the ANSI code page), the BOM, the line ends and every byte outside the edit stay as they were. A file of pure ASCII counts as UTF-8 without a BOM, so the first non-ASCII character typed into it makes it UTF-8. A character the file's code page cannot hold is not written: a strip offers to save the file as UTF-8 or to remove the character. A file that could not be written back exactly (binary, UTF-16 BE, text that does not decode cleanly) is not opened for editing.
• When the file changes elsewhere. With nothing unsaved, the new version is taken in (Ctrl+Z brings yours back); with unsaved edits, a strip asks whether to load the version on disk or to overwrite it. A read-only file can be edited and saved under another name. One file is edited in one FastMD window at a time.
• Recovery. Before a save overwrites anything, the bytes it replaces are copied to %LOCALAPPDATA%\FastMD\recovery, and the copy is deleted once the save has gone through. While edits cannot be saved (autosave off, a conflict, a read-only or missing file), a journal of them is written to the same folder 3 s after the last change. If a save was cut short, or edits were left in the journal, the next open of the file shows a strip: open the copy (it goes to %LOCALAPPDATA%\FastMD\copies), restore it, or delete it (to the Recycle Bin). Recovery files older than 14 days are removed. For a file encrypted with EFS they are encrypted too; a BitLocker To Go or VeraCrypt volume cannot be told apart, so the recovery files of a document there lie unencrypted in your profile.
• Limits. CJK input methods, the emoji panel (Win+.) and dictation do not type into the page itself: the window starts without IME, for speed. Latin, Cyrillic, dead keys, AltGr and switching the keyboard layout work, and all of them work in the source editors of formulas and diagrams. The Explorer preview pane and thumbnails stay read-only.

Privacy

FastMD neither collects nor sends anything about you: no telemetry, no identifiers, no analytics. It goes to the network in exactly two cases, and both are visible:

What	When	Where
Images from the document	if the document has an http(s) image and the setting is "Always" (the default) or you allowed it	to the addresses in the document itself, https only, no cookies and no authentication
Update check	once a day after the first frame, unless turned off in settings	api.github.com, one GET; the installer is downloaded only after you agree to it and is verified against a SHA-256

Everything else stays on the machine: settings in HKCU\Software\FastMD, reading positions and recent documents in %LOCALAPPDATA%\FastMD\positions.bin, the image cache in %LOCALAPPDATA%\FastMD\cache, crash reports in %LOCALAPPDATA%\FastMD\crashes (they are sent nowhere), the recovery copies and the journal of unsaved edits in %LOCALAPPDATA%\FastMD\recovery (see Editing). The Explorer preview pane does not go to the network at all.

Keys, settings and how the code is put together are described in app/README.md, the limitations of the current version and the roadmap in docs/PLAN.md, the history of changes in CHANGELOG.md.

Building from source

You need Windows 10/11 x64 and Visual Studio 2022 or newer: any edition, or the Build Tools, with the "Desktop development with C++" workload. CMake and Ninja come with VS.

pwsh -File app/build.ps1    # → app/build/Release/FastMD.exe

What is in the repository

Path	What is there
app/	the viewer itself
REPORT.md	the final report on choosing the stack
research/	six background reports: native UI, web engines, GPU stacks, the Markdown pipeline, Windows application startup, a survey of the products
bench/	the measurement harness and protocol, the test corpus, the results, descriptions of the 12 prototypes
docs/PLAN.md	the roadmap
docs/EDIT-MODE.md	the design of edit mode, the rule book its tests are written from

License

FastMD © 2026 seka. Distributed under the MIT License: the code may be used, changed and passed on freely, in open and closed projects alike, commercial ones included, as long as the copyright notice and the license text stay with it. Releases up to 1.3.0 came out under the GNU GPL v3.0.

Third-party libraries are bundled, all of them under MIT:

Library	What for	License
md4c	Markdown parsing	app/third_party/md4c/LICENSE.md
lunasvg and plutovg	SVG rendering	app/third_party/lunasvg/LICENSE
RaTeX	math typesetting	app/third_party/ratex/LICENSE-ratex.txt
mermaid-rs-renderer	Mermaid parsing and every diagram other than graph / flowchart	app/third_party/ratex/LICENSE-mermaid-rs-renderer.txt

The KaTeX fonts that are embedded into formulas are distributed under the SIL Open Font License.