Santoku

A no-nonsense markdown viewer: it opens a .md file and shows you the rendered document, instantly - the way an image viewer opens a photo.

Markdown is everywhere - READMEs, notes, specs, changelogs - but opening one still gives you a bad choice: a text editor showing raw # syntax, a heavyweight IDE that wants a whole workspace, or a website that asks you to upload your file. There’s no “double-click and it just appears” for markdown.

Santoku is that.

Santoku rendering a document on the desktop

Instant

Santoku drives your operating system’s own rendering engine instead of shipping a second browser. The result is a download measured in single-digit megabytes and a cold start to rendered text of well under half a second on ordinary hardware. It opens like a utility, because it is one.

Build	Size
Windows installer	~3 MB
macOS universal `.dmg`	~6 MB
Android APK	~8 MB
Web app (initial download, gzipped)	~64 KB - Lighthouse Performance 100

Reading comes first

The document is the interface. A slim top bar carries only what you need - open, theme, zoom - and then gets out of the way: scroll down and it slides away, scroll back up and it returns. Front-matter is lifted into a tidy metadata header instead of dumped as text. Nothing between you and the words.

Santoku’s empty state - open a file, or view a sample

It renders what you actually write

Full CommonMark, plus the GitHub-Flavored extensions people rely on:

Tables with column alignment
Task lists, tight and loose lists, nested to any depth
Strikethrough, inline code, links and autolinks
Footnotes
YAML front-matter, shown as a metadata card
Raw HTML is sanitized, never executed - scripts, iframes and event handlers are stripped

Every platform shares one rendering contract enforced by a conformance test suite, so a document looks the same whether you open it on a laptop or a phone.

Light theme Dark theme

Everywhere you have a file

Platform	How you get it
Windows	Installer or a portable `.zip` - run it from a USB stick, no admin rights
macOS	Universal `.dmg`, Apple Silicon and Intel
Linux	`.deb`, `.rpm`, or a portable AppImage
Android	Open any `.md` attachment or file and it renders instead of opening a text editor
Web	No install at all - and your file never leaves your device; there is no server and no upload

Light, dark, and follow-the-system themes on every one of them.

Quiet by design

No telemetry. No accounts. No update nags. No network calls you didn’t ask for - the web version literally has no code path that uploads a file. Santoku opens your document and does nothing else.

Download

Coming Soon

Still in a early stage (v0.1.0)

Santoku is early. What’s here works and is fast; a few things people will want are still on the way:

Set as default .md app / “Open with” - next up
Live reload - keep a file open beside your editor and watch it update on save
Syntax highlighting in code blocks, and richer image handling
In-document search and a table-of-contents outline