MDZip and Related Formats
MDZip didn't invent the idea of packaging Markdown with its assets — good prior work exists, and it deserves acknowledgment. This page maps the neighborhood and explains where MDZip fits.
TextBundle (and TextPack)
TextBundle pioneered the portable Markdown package: a bundle containing Markdown plus its assets, designed so editors could pass documents between sandboxed apps without losing images. TextPack is its ZIP-based single-file form.
TextBundle was born of the Apple ecosystem — created by macOS editor makers (Shiny Frog of Bear, alongside peers like Ulysses) specifically to solve document exchange between sandboxed Mac apps. The format itself is simple enough to implement anywhere, but its adoption remains overwhelmingly Apple-platform editors; "cross-platform" is true of the spec more than of the ecosystem.
MDZip shares TextBundle's philosophy while aiming at a broader target: not just a container convention, but a cross-platform ecosystem around it — open specification with a JSON schema, reusable core libraries for JavaScript/TypeScript and .NET, a CLI, editors and framework components, validation tooling, and first-class support for AI-generated documents.
Interoperability is a feature, not a rivalry: a TextBundle/TextPack importer is on the roadmap for the mdz CLI, and the import model translates external formats into MDZip without bending the specification around them.
MDZ — the independent Rust project
A separate, unaffiliated project — wflixu/mdz, with its Rust core mdz-rs, a CLI, and a VS Code extension — independently arrived at a strikingly similar design: Markdown plus assets in a standard ZIP, an index.md entry point, a manifest.json, its own specification, and even the same .mdz extension.
We read that convergence as validation: more than one team, working independently, concluded this is the right shape for portable Markdown. The two specifications are distinct and the projects are not affiliated — but given how much the layouts share, mutual compatibility is worth exploring, and we track it as an interoperability candidate alongside TextBundle on the roadmap.
EPUB
EPUB proved that ZIP-based document containers work at global scale — but its content format is XHTML, aimed at publication and reading systems rather than editing and authoring. Reading an EPUB requires a compatible reader; editing one is a specialist task. .mdz can be thought of as an EPUB-like container that is Markdown-native and radically lighter in structure. (More in the FAQ.)
DOCX and Open Packaging Conventions
Microsoft's .docx is also a ZIP of structured content and assets — the Open Packaging Conventions. It demonstrates two things MDZip leans on: the ZIP-container architecture is proven at massive scale, and users already have the mental model of "a document is one file with its images inside." The difference, again, is the payload: OPC wraps XML that only heavyweight tooling reads comfortably; .mdz wraps plain Markdown any text editor can open.
Comparison at a glance
| TextPack | EPUB | DOCX | .mdz |
|
|---|---|---|---|---|
| Container | ZIP | ZIP | ZIP | ZIP |
| Content format | Markdown | XHTML | OOXML | Markdown |
| Readable after unzip, in any text editor | ✅ | ⚠️ XML noise | ❌ | ✅ |
| Open, independent spec with schema | ⚠️ convention | ✅ | ✅ (complex) | ✅ |
| Primary orientation | editor interchange | publication | word processing | authoring and interchange and publishing |
| Cross-platform libraries, CLI, validation tooling | limited | readers mostly | proprietary-leaning | JS/TS + .NET libraries, CLI, editors, validators |
About the .mdz extension itself
The extension has had other tenants over the decades (a Microsoft Access wizard format, a compressed music module format in the Winamp era) — none current, but one legacy entry still triggers browser download warnings. That story, and its workarounds, has its own page.
The position, in one paragraph
TextBundle pioneered portable Markdown packages. MDZip shares that philosophy while focusing on a broader, open, cross-platform ecosystem — reusable libraries, tooling, validation, editor integrations, and AI workflows. Compete on ecosystem, cooperate on interoperability.
This page renders from related-formats.mdz — one self-contained file. Download it, open it in the web editor, or read how these pages are made.