MDowser

The plain-text web, rendered natively.
A minimal, fast, cross-platform browser for Markdown over HTTPS and local files.
No webview, no JavaScript, no cookies, no cache.

MDowser is a native desktop browser for the plain-text web. Paste an https:// URL or open a local Markdown file (file:///…, an absolute path or ~/notes.md) and it fetches or reads it, parses it once, and renders it with a clean, desktop-browser-style UI. The surface is deliberately small and auditable: one document format, one HTTP method, one network protocol — any static Markdown host just works.

• Native Markdown engine. CommonMark plus GFM-style extensions (tables, footnotes, tasklists, strikethrough) and YAML frontmatter, rendered by MDowser itself with a neutral documentation palette — code cards with syntax colors and a Copy button, striped bordered tables, callouts and documentation typography. HTML, JSX and ::: custom containers render at the markup level only: tags are transparent wrappers, MDX components (<Tabs>, <Accordion>, <Card>, <Steps>, <CodeGroup>, <Badge>) and their ::: equivalents (:::tabs, :::code-group, :::steps, :::card, :::accordion/:::details) draw natively, and :::/!!! admonitions become callouts — no JavaScript is ever executed. → docs/RENDERING.md
• Real browser chrome. Vertical tab rail, omnibox with address autocomplete (bookmarks, local history and a curated builtin list) and favicons, encrypted local history and bookmarks, zoom, light/dark theme, preferences and the internal about:home / about:history / about:licenses pages. → docs/INTERFACE.md
• Documents as they are. Color emoji, CJK and RTL scripts, images in PNG/JPEG/GIF/WebP/JPEG XL/AVIF/ICO/static SVG — decoded in pure Rust. In-page anchors, footnotes and bare-URL linkification included.
• Private by design. https:// only (never http://), GET only, no cookies, cache, proxy, webview or JavaScript; local files only from user input. A remote page can never name or load a local path. → docs/SECURITY.md
• Small and auditable. One binary, unsafe_code = "forbid", hard caps on every input, and a single document format to reason about. Rendering is incremental: code blocks draw only the lines on screen, tables fingerprint once per document, and the palette is interned. → docs/ARCHITECTURE.md

Prebuilt archives for macOS, Linux and Windows are attached to every release:

• macOS: the .app is ad-hoc signed, not notarized: double-click it once so Gatekeeper registers the block, then allow it in System Settings > Privacy & Security > Open Anyway (right-click > Open no longer bypasses this on current macOS).
• Linux: sudo dpkg -i mdowser_<ver>_amd64.deb (or arm64), or sudo rpm -i mdowser-<ver>-*.rpm, or flatpak install mdowser-<ver>.flatpak. The package installs the desktop entry, hicolor icon and AppStream metadata, so MDowser appears in the applications menu and its Software-center page.
• Windows: unzip and run mdowser.exe (on Windows on ARM use the aarch64 zip; the x86_64 one also runs there via emulation). The .exe is unsigned: on the SmartScreen warning click More info > Run anyway; see docs/NAVIGATION.md to register .md files.

SHA256SUMS.txt travels with every release.

make        # deps + host release + current-OS dist into dist/
            #   macOS: universal .app.zip | Linux: tar.gz/.deb/.rpm/flatpak | Windows: .exe
make dist   # deps + host release + EVERY platform into dist/ (macOS, Linux, Windows)
make install   # install into /usr/local (PREFIX/DESTDIR honored; `make dist-rpm` for RPM)
make run    # debug build + run

make and make dist install what the host is missing first (make deps; SKIP_SETUP=1 opts out). Requires stable Rust ≥ 1.98 and a C compiler (plus NASM on x86/x86_64 hosts; ARM64 hosts assemble with the system toolchain and need none). On native Windows without make, windows.ps1 is the equivalent entry point (see docs/BUILDING.md). Full requirements, the make test pipeline and multi-OS make dist packaging: docs/BUILDING.md.

mdowser ~/notes.md                     # local document
mdowser https://example.com/readme.md  # remote document

Type an address or path in the omnibox, or open a file with the app. Every navigation stays inside MDowser; Esc stops a load. See docs/NAVIGATION.md for the route cascade and local file rules.

All shortcuts: docs/INTERFACE.md.

• docs/RENDERING.md — everything Markdown can put on screen.
• docs/INTERFACE.md — the desktop UI, element by element, plus all shortcuts.
• docs/NAVIGATION.md — URL routes, redirects, local files and file associations.
• docs/BUILDING.md — toolchain, make pipeline, packaging and runtime requirements.
• docs/ARCHITECTURE.md — module map, contracts and the performance model.
• docs/SECURITY.md — threat model, hard caps and vulnerability reporting.
• docs/CONTRIBUTING.md — quick start and code standards.
• CHANGELOG.md — every notable change and fixed bug.
• THIRD_PARTY_NOTICES.md — licenses of the bundled dependencies and fonts (also rendered in-app: Preferences → View third-party licenses).

The network contract is deliberately tiny: https:// only, GET only, one Markdown content type, no cookies, cache or proxy, and local files only from user input (or links inside a local document) — a remote page can never name or load a local path. Every read and decode path is hard-capped (10 MiB documents, 16 MiB / 48 MP images, 1M events, bounded encrypted history and bookmarks), SVG is rasterized statically and unsafe_code = "forbid". The full threat model and caps are in docs/SECURITY.md.

• Optional cache (deliberately cacheless today).
• Per-block unique indent ids, tab drag-reorder.

Mozilla Public License 2.0 (MPL-2.0) — see LICENSE.

MDowser is an independent project, not affiliated with, endorsed by or sponsored by any product, project or service it may mention. Every third-party name and mark belongs to its respective owner and is used only for identification or description; bundled dependencies are listed in THIRD_PARTY_NOTICES.md.