Markdown Desk

A complete markdown reading, writing & annotation desk — in one HTML file.

By Andrew Michelis · KnackMentor open tools · Apache-2.0 licensed

Markdown Desk is a single self-contained markdown-desk.html (one HTML file, zero dependencies, zero telemetry) that turns Chrome or Edge into a Joplin-style workspace for your local markdown files: project trees, live-styled editing, highlights, notes, bookmarks, stylus ink and text labels, WYSIWYG PDF export, ZIP snapshots, and PWA installation. Everything stays on your machine.

Why

Plain text is the most durable format there is — Markdown Desk is built around keeping it that way. Your .md files remain clean, human-readable text forever (pasted images become real files beside them, never base64 blobs); annotations live in transparent .mdesk JSON sidecars that travel with your folders; and the tool itself needs no server, no account, no install, no build step. Open the file, open your folder, work.

Highlights

• Write — three-pane modes (edit / split / preview, preview on the left), a full formatting toolbar, and live markdown styling right in the plain-text editor: **bold** looks bold, headings stand out, syntax characters stay visible.
• Read — project folder tree, outline, adjustable article width & zoom, light/dark themes, in-app link navigation.
• Annotate — text highlights with robust re-anchoring, per-document notes, bookmarks, and a real ink layer: markers, pens, shapes, text labels with font/size/color — all element-anchored so they track your text through reflows, with group selection, cross-window copy/paste, and deep undo.
• Export — pixel-faithful PDF with your annotations baked in, ink-layer PNG, and one-file ZIP snapshots of a whole project (with a read-only Review mode for received snapshots).
• Own your data — IndexedDB + sidecar files only; a one-shortcut privacy wipe; nothing ever leaves the browser.

Quick start

1. Download markdown-desk.html.
2. Open it in Chrome or Edge (the File System Access API is required for folders and saving).
3. Ctrl+O a file — or open a whole folder from the sidebar and let it map your docs.
4. Press F1-style Help (the ? button) for the complete shortcut table.

Works from file:// or any static host. To install it as an app (PWA) with offline support, serve it over https and upload the four files from Help → Download PWA kit next to it — the tool detects them automatically.

Documentation

• User manual — every feature, workflow, and shortcut.
• Requirements specification — the full engineering spec: 100+ numbered requirements, regression guards, and the testing strategy this project is developed against.

Privacy

No network calls for core function, no analytics, no accounts. Data lives in your browser (IndexedDB / localStorage) and in .mdesk sidecar files you can read, diff, and delete yourself. Ctrl+Shift+R inside the tool wipes everything browser-side.

Related tools

Part of a small suite of open tools by Andrew Michelis. See them all at knackmentor.com/work.

• av-integrity: detect when a vehicle's sensors are lying (an open AV sensor-fusion and integrity monitor).
• WebClip: save any web page exactly as you saw it (a pixel-faithful page-to-PDF Chrome extension).
• HashTag Language: a small notation for facts, queries, and provenance (the shared substrate these tools speak).

_{Built in the open, verified before shipping. The standard behind KnackMentor.}

Verifying a release

Every release is tagged and signed under the author's key, and the full source is public here, so you can build from source and compare. Authorship and first-conception are independently timestamped (RFC-3161 / OpenTimestamps) as part of the author's provenance process. Release-artifact attestation via Sigstore is planned. Any certification or curation offered on top stays opt-in, self-hosting is always allowed, and there is no certificate authority you are required to trust.

License, attribution & citation

Apache License 2.0 — see LICENSE. Copyright © Andrew Michelis (KnackMentor). If this tool is useful in your work, a citation is appreciated: GitHub's Cite this repository button uses CITATION.cff.

Embedded libraries: marked 12.0.2 (MIT), DOMPurify 3.1.6 (Apache-2.0/MPL-2.0).

Give it a try here

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Built and maintained by KnackMentor — automation & systems-integration consulting, Athens, GR.