Read Markdown files, formatted

Drop a .md file, open one or paste text. It is shown the way GitHub shows it: headings, tables, task lists, footnotes and code, with a contents list. Edit beside the formatted page (above it on a phone), copy the clean HTML or print it.

Free. No ads, no paid extras, no tracking, no sign-up. Nothing you put here is sent anywhere.

or drop them here, or paste text

Sample. A short document written for this page, to show what it does. Drop, open or paste your own to replace it.

Contents

Nothing of your file is sent. The file stays in this browser tab. After load nothing is fetched. One exception: when a very slow conversion is stopped for a newer text, the page starts its own script again; the browser normally reads it from its cache, and if the cache is turned off it asks this site for that one file, a request that carries none of the text. A picture on another site is never fetched: it is shown as a box with its address. To check: open your browser's network panel, then drop or paste a file; no request appears but that one exception (a picture written into the text or opened with the file is listed as a data: address). On zeromile.tools this page is served with connect-src 'none' and pictures only from this site or as data: addresses, so the browser itself refuses anything else.

How this works

Shown: CommonMark with GitHub's additions: tables, task lists, strikethrough, automatic links, footnotes, headings with links, fenced code, block quotes. The header block at the top of a file (between --- lines) is shown as a small table.
Views: Read shows the document with a contents list built from its headings. Edit puts the plain text beside it (above it on a phone), and the formatted side follows as you type. A file opens in Read, pasted text in Edit.
Safe: Web code written inside the text is cleaned by DOMPurify, keeping only a short list of harmless tags (such as details, kbd, sup, tables and lists): no scripts, frames, forms, styles or event attributes. Web links (http and https) open in a new tab and mail addresses in your mail program; a link to a place in the document goes there, and a link to a file opened together with this one opens it here; any other link is not followed.
Pictures: Pictures written into the text (data:) and pictures you open together with the file are shown. A picture on another site is never fetched: you see its description and its address instead.
Several files: Open or drop several files at once: a link from one to another opens it here, and pictures named by their file name are shown.
Speed: The conversion runs in a background worker, so typing never waits for it; long documents appear part by part, the first screen first. Typing in Edit slows down on a text longer than about 1 MB or 50,000 lines (the plain text box lays out every line at each key): such a text opens in Read, and Read is not affected.
Kept: Nothing. Close the tab and the text is gone.
Not in this version: Diagrams (mermaid) and mathematics are shown as their text. Code is not coloured. Some GitHub touches are not drawn: alerts such as [!NOTE] show as a plain quote, emoji codes such as :tada: stay as text, ~one tilde~ is not struck through, and footnote marks keep their brackets. No opening of a whole folder, no saving of files: use Copy as HTML or Print.
Open source: markdown-it with markdown-it-footnote (MIT licence), linkify-it, mdurl, uc.micro and punycode.js (MIT), entities (BSD licence), DOMPurify (Apache 2.0 or MPL 2.0 licence).