If you've ever built an application that streams responses from an AI, you know the feeling. You watch, token by token, as the text appears. But you also see the flicker of unstyled text... the code blocks that don't look like code until the very last backtick... the bold text that suddenly snaps into place at the end.
It works, but it feels... unfinished. The user experience is jarring.
What if rendering streaming content could be as smooth and seamless as the AI generating it?
Meet Streamdown. It’s an open-source, drop-in replacement for react-markdown, but re-imagined from the ground up for the world of streaming AI.
The problem with most Markdown libraries is that they were designed for static content. They need the entire block of text to be complete before they can format it correctly.
Streamdown is different. It’s built to intelligently parse and style incomplete Markdown. That means as the tokens stream in, Streamdown is already applying formatting. Incomplete bold text? It’s already bold. An unterminated code block? It’s already styled as code. The result is a fluid, professional user experience, with no jarring layout shifts.
And getting started is incredibly simple. Because it’s a drop-in replacement for react-markdown, you can often switch over with just a one-line change in your import statement.
But Streamdown doesn't stop at streaming. It’s a full-featured powerhouse.
You get full support for GitHub Flavored Markdown—think tables, task lists, and strikethroughs.
Need to display complex formulas? It renders LaTeX equations beautifully using KaTeX.
One of its standout features is support for Mermaid diagrams. Just stream a Mermaid code block, and Streamdown provides a button to render it into a crisp, clear diagram right in the UI.
And of course, it comes with gorgeous, server-side code syntax highlighting via Shiki, making your code snippets pop.
Under the hood, Streamdown is built for the real world. It’s security-first, using harden-react-markdown to keep your application safe. And it’s performance-optimized with memoized rendering, ensuring your UI stays fast and responsive, even with rapid-fire updates.
Streamdown is the missing piece for creating polished, professional-grade AI experiences in React. It bridges the gap between the raw power of streaming models and the refined interface your users expect.
So if you're building with streaming AI, stop fighting with your Markdown renderer. Head over to npm, install Streamdown, and give your users the seamless experience they deserve.
