Markdown exists because writing HTML by hand for every paragraph and list is slow. HTML exists because Markdown, by design, can't express most of what a real web page needs. They're not competitors so much as two tools for two different stages of writing.
What Markdown is actually good at
Markdown covers the formatting that shows up in the vast majority of written content: headings, bold and italic text, links, lists, blockquotes, and code blocks. The syntax is close enough to how people already write plain text — **bold**, - a list item — that it doesn't get in the way of thinking about the writing itself. That's the entire pitch: fast to write, fast to read even unrendered, and portable across GitHub, Notion, Slack, static site generators and nearly every modern editor.
Where it runs out of road
Markdown has no native way to express a multi-column layout, a styled button, a specific class name for CSS, a <table> with merged cells, custom attributes, or embedded interactive components. Most Markdown flavors (GitHub-flavored Markdown included) add a basic table syntax, but anything beyond that typically falls back to writing raw HTML directly inside the Markdown file — which works, but at that point you're not really avoiding HTML, just using it selectively.
This is the practical dividing line: Markdown for the writing itself, HTML for anything structural or visual that the writing needs to sit inside.
Converting between them
Markdown to HTML is the easy direction — it's effectively lossless, since every Markdown construct maps onto a specific, well-defined HTML element. Our Markdown to HTML tool does exactly this conversion and sanitizes the output before rendering it, so the preview is safe even if the source Markdown contains stray HTML.
HTML to Markdown is lossier by nature. A <div> with a custom class, an inline style attribute, or a complex nested table doesn't have a Markdown equivalent, so a converter either drops that information or falls back to embedding the raw HTML inline. Our HTML to Markdown tool handles the common cases — headings, paragraphs, lists, links, basic tables, code blocks — cleanly, which covers most content copied out of a rich text editor or a web page, but highly styled source HTML will carry over some rough edges.
A rule of thumb
If you're writing documentation, a README, a blog post, or notes that need to move between tools unchanged, write it in Markdown. If you're building a page that needs specific visual structure — a landing page, an email template, anything with real layout requirements — write HTML, or write Markdown for the prose and drop in HTML only for the parts that actually need it.