OnlineCodeEditor

Markdown editor with a sanitised live preview

Tables, task lists and fenced code blocks render as you type. The last line of the example tries to run a script; the sanitiser removes it.

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Safe by construction

Markdown is converted with marked and the resulting HTML is cleaned with DOMPurify before it reaches the preview. The preview frame also runs with an opaque origin and no network access, so even a sanitiser bypass could not read your projects or send data out.

Writing features

The outline panel lists headings so you can jump through long documents, and Prettier formats Markdown tables and lists consistently. Snapshots keep earlier drafts you can compare side by side.

How to use it

  1. Edit README.md and watch the preview.
  2. Open Outline to jump between headings.
  3. Download the file from the file tree.

Questions

Which Markdown flavour is used?

GitHub-flavoured Markdown as implemented by marked: tables, task lists, strikethrough and fenced code.

Can I embed HTML?

Basic HTML is kept, but scripts, event handlers and other unsafe content are removed by DOMPurify.

Can I export to PDF?

Use your browser’s print dialog on the preview for PDF. The editor exports .md files and ZIP archives.