NanoMD Chrome Extension

Last updated 2026-10-29

The NanoMD extension is a Markdown viewer for Chrome that renders local Markdown files with the same parser this site documents. Open a .md file and get an editor and a live Markdown preview side by side, with no code and no server.

Install

Install NanoMD from the Chrome Web Store.
Turn on file access (below).
Drag a .md or .markdown file into Chrome, or open its file:// path.

Turn On File Access

ImportantChrome keeps extensions off file:// pages by default. Until Allow access to file URLs is on, NanoMD never runs and the file stays plain text.

Open chrome://extensions.
Click Details on NanoMD.
Turn on Allow access to file URLs.

Reload any Markdown tab that was already open.

Editing and Preview

Area	Behavior
Left	Source editor holding the file content
Right	Preview rendered with `MDParser.Parse().html()`; re-renders 200 ms after typing stops
Bottom	Footer linking to the NanoMD repository

Every syntax on this site works in the preview, including Mermaid, math and Chart.js blocks. Mermaid, KaTeX, Chart.js and code-prettify are bundled in the extension and load from its package, so diagrams and formulas render offline.

Saving

Action	Result
Typing in the editor	`●` appears in front of the tab title
First `Cmd/Ctrl + S`	A save dialog suggests the current file name; the chosen file is written and `●` clears
Later `Cmd/Ctrl + S` in the same tab	Overwrites the same file without asking
Cancel the dialog	Nothing is written; the edits stay in the editor

Chrome cannot write back to a file:// page directly, so the first save always asks for the target; pick the original file to overwrite it. Closing or reloading the tab discards unsaved edits.

Scope

Runs only on file:///*.md and file:///*.markdown; Markdown served from a website is left as is.
Requests no extension permissions and sends no requests of its own. Remote images, videos and YouTube / Vimeo embeds written in the file load like on any web page.

See the privacy policy for the full data handling.