StreamMDX vs Streamdown

This page is a practical comparison to help you choose the right tool and understand the tradeoffs.

High-level positioning

• Streamdown: a drop-in replacement for react-markdown optimized for streaming/incomplete markdown via memoization + unterminated-block recovery (remend).
• StreamMDX: a worker-first incremental patch pipeline designed for high-frequency updates and large documents, with backpressure guardrails.

Architecture

Streamdown

• Main-thread parsing/rendering (React component)
• Focus on resilient markdown formatting while content is incomplete/unterminated
• Single-package distribution (streamdown)

StreamMDX

• Worker-first parsing (off main thread)
• Incremental diff → patch batches → patch scheduler applies to a stable render tree
• Separate hosted worker bundle (/workers/markdown-worker.js) recommended for production CSP
• Modular packages + convenience wrapper (stream-mdx)

Developer experience

• Streamdown is “install and render” for users already using react-markdown.
• StreamMDX requires hosting a worker bundle (or allowing blob:), but provides stronger responsiveness and long-document guardrails.

Security

• Streamdown emphasizes hardened rehype pipelines (e.g., rehype-harden) and runs in the main thread.
• StreamMDX sanitizes HTML by default and can isolate parsing/enrichment in a worker; CSP posture is clearer when you host the worker bundle.

Tradeoffs

When to choose which

• Choose Streamdown if you want drop-in react-markdown compatibility and a minimal setup.
• Choose StreamMDX if you need worker isolation, high-frequency streaming stability, or long-document responsiveness guardrails.