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Writing & developer utilities · browser-local

Markdown ↔ formatted HTML converter

Paste Markdown or formatted HTML on either side. Aftermath detects the format, updates the other side immediately, and keeps the content in this browser.

Work happens in the current browser. The route does not require an account or a server-side processing job.

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Interactive browser workspace

Markdown ↔ formatted HTML converter

The live tool is loaded in this browser only. This route does not need camera, microphone, or screen-capture permission for its main task.

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What it does

Useful, focused capabilities

  • Automatic Markdown or formatted HTML detection
  • Live two-way editing with an immediate converted view
  • Safe formatted output with active content and unsafe links removed
  • Copy as Markdown and copy as formatted HTML only after validation
  • No upload, account, or server-side conversion

Browser compatibility

Requirements and honest fallbacks

JavaScript and a modern browser with contenteditable and clipboard support for the best editing and copy experience.

  • JavaScript
  • Clipboard API
  • rich HTML clipboard support

Questions people ask

Clear answers and limits

Does this Markdown converter upload my text?

No. Parsing, sanitizing, conversion, and copying happen in the current browser. The tool has no content upload path.

What does copy as formatted do?

It copies sanitized text/html when the browser supports rich clipboard writes, with readable plain text as the fallback. Unsafe active content is never copied.

Why are the copy buttons disabled?

Copy is enabled only when the current side contains valid, non-empty content. An unclosed Markdown code fence or unsafe formatted markup must be corrected first.

How to use this tool

Convert Markdown and formatted HTML locally when you need to review, format, sanitize, or copy text between the two representations. The browser keeps the entered content in the current session and removes unsafe active markup before the supported copy actions. Review the resulting text before use because a clean conversion does not validate a publishing system, schema, or destination policy.

What to choose and what you get

What to choose

  • Markdown text
  • formatted HTML text

Result

  • copyable Markdown and formatted text with a live preview; no direct file download

Supported use

  • Markdown fences, formatted markup, unsafe active content, and clipboard eligibility are validated before copy actions.

Supported formats

  • Accepted formats: plain text.
  • Output formats: Markdown, HTML.

Browser support and permissions

  • Modern browser with JavaScript; clipboard, DOM, and download behavior varies by browser.
  • No camera, microphone, or screen permission is needed.

Worked example

A local Markdown note needs safe formatted HTML for copying, followed by a round-trip check back to Markdown.

Starting facts

  • The entered text stays in the browser.
  • Active markup and unsafe attributes must not survive conversion.

Observed operation: Convert Markdown to sanitized formatted HTML, edit either pane and block copy actions when the current content is invalid.

Review the result: Compare headings, lists, links and line breaks in both directions before copying the required representation.

Boundary: Conversion cannot preserve every HTML feature, styling system, extension syntax or unsafe active content.

What you can do

Markdown to HTML and HTML to Markdown conversion

Next step: Choose a related route when the input, output, or required workflow is different.

If it does not work

  • Route-specific verification can require a warning or failed result instead of a download.

Things to know

  • Unsafe active markup is removed; clipboard rich-write support varies by browser.

Privacy boundary

Entered text stays in the current browser session and is not sent to an Aftermath processing service. How local processing is verified.

What this tool verifies

Checks the displayed limits and reports or creates copyable Markdown and formatted text with a live preview; no direct file download from Markdown text; formatted HTML text.

Check before sharing

The result describes the text entered in this browser; it is not an external certification.

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