# Streaming HTML

> Use when reviewing server-side rendering setup, Next.js App Router pages, or Node.js HTTP handlers to verify that HTML is streamed incrementally rather than buffered until completion.

- Skill: `thedaviddias/streaming-html` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add thedaviddias/streaming-html`
- Raw SKILL.md: https://api.skillmd.com/api/skills/thedaviddias/streaming-html/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- Author: thedaviddias (https://skillmd.com/u/thedaviddias)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/thedaviddias/streaming-html

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# Stream HTML to the browser before the full response is ready

Traditional SSR waits for all data fetches to complete before sending a single byte of HTML, which means the browser cannot parse, discover subresources, or render anything until the slowest data query finishes. Streaming decouples the delivery of above-fold content from slow database queries and third-party API calls, dramatically improving perceived performance and LCP.

## Quick Reference

- Streaming sends HTML in chunks as it is generated instead of waiting for the full response
- React renderToPipeableStream and Next.js App Router stream by default when you use Suspense
- Place Suspense boundaries around slow data dependencies to flush above-fold HTML immediately
- Monitor TTFB in Lighthouse — values above 600ms are a sign that streaming is not being used

## Check

Examine this server-side rendering implementation to determine whether HTML is streamed in chunks or buffered until fully generated before sending to the client.

## Fix

Refactor the SSR implementation to use renderToPipeableStream with Suspense boundaries around slow data fetches, or use ReadableStream in a Node.js handler, so that above-fold HTML is flushed to the client immediately.

## Explain

Explain how streaming HTML improves TTFB and FCP by decoupling the delivery of fast content from slow server-side data dependencies.

## Code Review

Review server entry points and page components for renderToString calls, missing Suspense boundaries around data-fetching components, and use of await on slow queries before returning a response.

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For full implementation details, code examples, and framework-specific guidance,
see `references/rule.md`.

Rule page: https://frontendchecklist.io/en/rules/performance/streaming-html