@tschk/svelte-streamdown

A Svelte 5 markdown renderer for AI-powered streaming applications.

Port of Vercel Streamdown for Svelte 5. Forked from beynar/svelte-streamdown.

Install

npm install @tschk/svelte-streamdown

Requires Svelte 5.

Usage

<script>
  import { Streamdown } from "@tschk/svelte-streamdown";
  import "@tschk/svelte-streamdown/styles.css";

  let markdown = $state("**Hello** world");
</script>

<Streamdown {markdown} />

Props

| Prop | Type | Default | Description | | -------------------------- | -------------------------- | ------------- | ---------------------------------------------------------------- | | markdown | string | "" | Markdown content to render | | mode | "streaming" \| "static" | "streaming" | Streaming mode repairs incomplete syntax; static renders as-is | | dir | "auto" \| "ltr" \| "rtl" | "auto" | Text direction. auto detects per-block | | animated | boolean \| string | false | Animation: true (fade), "blur", "slide-up", "slide-down" | | caret | boolean \| string | false | Caret at end ("block", "circle", or custom char) | | parseIncompleteMarkdown | boolean | true | Enable incomplete markdown repair | | normalizeHtmlIndentation | boolean | false | Remove extra indentation from HTML blocks | | rehypePlugins | PluggableList | [] | Additional rehype plugins | | remarkPlugins | PluggableList | [] | Additional remark plugins |

Features

• Streaming-optimized with incomplete markdown repair (remend)
• Code highlighting via Shiki with dual-theme CSS variables (light + dark)
• Code blocks with language label + copy button
• Mermaid diagrams (opt-in, install mermaid peer dep)
• Math via KaTeX (opt-in, add remark-math + rehype-katex)
• CJK punctuation handling
• GitHub Flavored Markdown (tables, task lists, strikethrough)
• Security via rehype-harden
• CSS-framework-agnostic (plain CSS, Tailwind, UnoCSS, etc.)

See full documentation for theming, animations, plugins, and comparison with upstream.

License

ISC. Apache-2.0 upstream license (Vercel Streamdown) retained in LICENSE-APACHE.