Free Markdown to HTML converter – with page preview

Markdown is a way of writing text in which you mark formatting with plain characters. A line that starts with # becomes a heading, and a word wrapped in two asterisks on each side becomes bold. Its creator, John Gruber, describes Markdown as a text-to-HTML conversion tool for web writers[1]. Version 1.0.1 came out on December 17, 2004[1].

HTML is the core markup language of the World Wide Web[2]. It describes a page with tags in angle brackets, for example <h1> for a heading and <strong> for bold text. The browser reads those tags and lays out the page from them.

Gruber put the split between the two formats in one sentence: HTML is a publishing format, and Markdown is a writing format[3]. That is why the text gets written in Markdown, while the page receives the HTML produced from that text.

Paste your text into the Markdown field or add a file with the Add Markdown file link, then click Convert. The finished code appears in the HTML field. A line starting with # gets an h1 tag there, text wrapped in two asterisks on each side gets a strong tag, and lines starting with a hyphen become a ul list.

Next to the HTML field there are two view buttons. HTML code shows the tags, which you can copy with Copy or save with Download as converted.html. Preview shows the same result as a page, so you can see whether the table has columns and the list has bullets.

If the file starts with a front matter block from Jekyll or Hugo, the tool skips it and shows a notice under the result. The conversion uses the marked library, whose documentation lists 99 percent compliance with the CommonMark 0.31 spec[4]. For the reverse direction, from page code back to Markdown, use the HTML to Markdown converter.

The authors of the CommonMark spec state plainly that Gruber’s original syntax description does not specify the syntax unambiguously[5]. Each program therefore settled the unclear cases in its own way. The spec gives the example of a document that renders one way in a GitHub wiki and another way after conversion with Pandoc[5]. So its authors wrote the syntax out as rules with examples. The current version of the spec, 0.31.2, dates from January 28, 2024[5].

GitHub described its own variant, GitHub Flavored Markdown, which covers the whole CommonMark spec plus five extensions[6]. They are tables, task lists, strikethrough, autolinks and a filter for selected HTML tags. A table and a task list from a README file therefore come out of this converter as an HTML table and a list with checkboxes.

The static site generators Jekyll and Hugo read a front matter block with the post’s metadata from the top of the file. Jekyll requires that block to be the first thing in the file and to be YAML set between triple-dashed lines[7]. Hugo also accepts TOML between lines of three plus signs[8]. You can read metadata written in YAML as an object with the YAML to JSON converter.