MackDown↓
Markdown, turned on its head.
A Markdown viewer for Windows that opens before you've finished double-clicking. Three megabytes. No browser inside. No account. No sidebar that wants to be your friend.
Latest release: …
hero.md — ƜackDown · Cyberpunk Terminal
In the app you press T. Here you have to click, like an animal.
Nutrition Facts
Serving size1 .md file
Download size~3 MB
Browser engines0
Background services0
Accounts required0
Telemetry0 g
Fonts, embedded3 cuts
Themes8
Percent daily values are based on a 2,000-tab diet. Contains Rust. Processed on GPUs that also process games.
#A short history of opening a text file
- 1995 — You double-click
readme.txt. Notepad appears. Instant. Nobody is impressed; that's just how computers work. - 2008 — Markdown exists now. You open a
.mdin a text editor and squint at the asterisks. Instant, but ugly. - 2016 — A beautiful Markdown app appears. It ships its own web browser to draw headings. Four seconds, then a "What's new" tab.
- 2022 — Same app, now with sync, plugins, an AI assistant and a 400 MB update. You wanted to read a to-do list. Six seconds and a login prompt.
- 2026 — ƜackDown. One small executable that talks straight to the graphics card. The first screen of a 40,000-block document lays out in about 2 milliseconds; the rest finishes while you read. Instant again. Nobody is impressed. That's the point.
Times for other apps are from memory and mild resentment, not benchmarks. The 2 ms figure is from our own test suite on an ordinary desktop. Your mileage may vary; it will still be short.
#Things ƜackDown will never do
A feature list, but for the features we're proudest of not having.
- Ask you to create an account
- Sync to a cloud
- Show a splash screen
- Open a "What's new" page
- Install a background updater
- Offer a plugin marketplace
- Run on macOS or Linux
- Grow an AI sidebar
- Manage your files for you
- Render HTML, ever
- Phone home
- Take four seconds to open a list
#What it does instead
Opens huge files instantly
It lays out only what fits on your screen before the window appears, and does the rest a few milliseconds at a time while you read. The scrollbar politely estimates the length until it knows.
Draws with the GPU, not a browser
Direct2D and DirectWrite, straight from Rust. Every frame is timed to your monitor's refresh rate, so scrolling and zooming feel like they belong to the OS, because they do.
Eight themes, zero CSS
Cyberpunk Terminal, Tokyo Dusk, Monokai Pro Rust, Nordic Fjord, Solarized Deep Dark and Paper & Gutenberg, plus Monochrome Light and Dark for boring people. The picker can follow the Windows light/dark setting. Write your own in a few lines of JSON.
Pictures, finally
Local PNG, JPEG, GIF, BMP and WebP are drawn with the Windows imaging codecs and scaled to the column. Remote images show their alt text, because there is no network code to fetch them with.
Built for agent output
A file that is still being written reloads as it grows, the blocks that changed light up for a moment, and if you were at the end you stay at the end. Every file reopens where you left it. Ctrl Shift A keeps the window above your editor.
Prints. To paper, or to PDF.
Ctrl P opens the Windows print dialog; pick Microsoft Print to PDF and you have a PDF. Pages break between blocks, dark themes print in grayscale, and no browser was harmed.
Brings its own typeface
Iosevka, in monospace, sans and serif cuts, embedded in the exe. Your documents look the same on every machine, including the one where somebody uninstalled the fonts.
Reloads when you save
Keep your real editor open next to it. Hit save, and ƜackDown has already redrawn by the time you look over. No "file changed on disk" dialog, because what else would you want?
Code blocks that respect identifiers
Long lines scroll sideways instead of wrapping in the middle of Api.Integrators. Syntax colors for a dozen languages. A Copy button appears when you hover, then goes away again.
Math, within reason
TeX becomes Unicode: $E = mc^2$ renders as E = mc², \alpha \leq \beta as α ≤ β. Matrices and other things Unicode can't say are shown as source, honestly, instead of wrong.
The extensions people actually use
Tables, task lists, footnotes that link both ways, callouts with real icons, definition lists, [[wiki links]], H~2~O, 2^10^, {#custom-ids}. Mermaid diagrams are shown as code. We're sorry. We're not that sorry.
Keyboard first
Everything is a key away: zoom, themes, back, select all, copy, a help page on F1. The mouse is welcome too. It just isn't required.
#Weight class
Installed size. Lower is better, unless you enjoy progress bars.
Apollo guidance computer, total memory
72 KB
ƜackDown, fonts included
3.2 MB
Windows 95, the whole operating system
~50 MB
A typical "lightweight" note app
~250 MB*
* Estimate. It's always an estimate; it updated itself while we were measuring. We tried to fit on a floppy. Two floppies. We'll keep trying.
#Keys
Theme picker with live previewCtrl T
Next / previous themeT / Shift T
Zoom, 4% to 5000%, centered on the cursorCtrl + wheel
Reset zoomCtrl 0
Scroll a wide code block sidewaysShift + wheel
Page down / upSpace / Shift Space
Top / bottomHome / End
Open a fileCtrl O or drop it on the window
Find in pageCtrl F, then Enter / F3
Back / forward, after following a linkBackspace / Alt →
Everything above, for mouse peopleRight-click
Select all, copy (plain and formatted)Ctrl A, Ctrl C
Print, or save as PDFCtrl P
Always on topCtrl Shift A
Reload file and themesF5
Help, with a tour of every featureF1
#Questions people might ask
Does it run on macOS?
No. ƜackDown talks directly to Windows' graphics stack, which is the entire reason it's small and fast. A port would mean a portability layer, and then we'd be the thing we're making fun of.
Linux?
Also no. See above, but with more goodwill.
Can I edit files with it?
No. You already have an editor you like. Open the file there, keep ƜackDown next to it, and every save shows up instantly. Two small tools beat one big one; this was known in 1995.
Why is the M upside down?
Because it's Markdown, turned on its head. The letter is Ɯ, U+019C, "Latin capital letter turned M". It has been sitting in Unicode since 1993 waiting for a job. We gave it one.
Windows says it doesn't recognize this app.
Correct, and Windows is being honest: the files aren't code-signed yet, because certificates cost either money or reputation and we're starting with neither. Click More info → Run anyway, or verify the SHA-256 checksum published with every release, like the responsible adult you are. Starring the repo helps us qualify for free signing. That's not a joke; it's literally how the program works.
Where does it keep my settings?
One tiny JSON file in %APPDATA%\WackDown that remembers your theme, zoom, window size, whether you pinned it on top, and where you were in the last hundred files. Drop your own themes in a folder next to it. That's the whole configuration story.
How far can I zoom?
From 4%, where a document becomes a mood, to 5,000%, where a comma becomes a landscape. Most apps stop at 200% because nobody asked. We asked. There's something waiting for you at both ends.
Does it support images?
Local ones, yes: PNG, JPEG, GIF, BMP, WebP, decoded by Windows and scaled to the column. Remote ones show their alt text, because there is no network code. Mermaid diagrams are shown as code, which is technically rendering.
Who wrote this?
An AI coding assistant (Claude Code), with a human holding the leash, reviewing the work and making the rude design decisions. The code is GPL-3.0, so you can read every line and judge for yourself.
#Install in three steps, one of which is a warning
- Download the installer (or the portable exe, if installers aren't your thing). Windows 10 or 11, 64-bit.
- Run it. It installs for your user only, so there's no admin prompt, and it offers to open
.mdfiles politely, without stealing them from an app you've already chosen. - Double-click a Markdown file. Blink. Notice that you didn't need to.
SmartScreen will frown. The release isn't signed yet (see the questions above). Choose More info → Run anyway, or check the file against SHA256SUMS.txt on the release page first.