vercel-react-best-practices

A checklist of React and Next.js coding practices from Vercel Engineering, focused on keeping web applications fast. React is a JavaScript interface library, and Next.js is a framework built around it.

In plain words
What is it for?
Writing, reviewing, or refactoring React components and Next.js pages, especially their data fetching, rendering, server-side work, and bundle size.
Why use it?
It helps prevent common slowdowns such as unnecessary waiting, oversized browser code, excessive updates, and inefficient data loading.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/atman36/codex-maintainer-kit/react-best-practices
Any agent
npx skills add Atman36/codex-maintainer-kit --skill react-best-practices
Clone the repo
git clone --depth 1 https://github.com/Atman36/codex-maintainer-kit

Made for: Claude Code, Codex.

Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,499 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 78% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00067 $0.01499
Opus 5 $0.00034 $0.00749
Sonnet 5 $0.00013 $0.00300
Haiku 4.5 $0.00007 $0.00150

Measured 2d ago against content hash 61860fd4249c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

vercel-react-best-practices scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

78% identical to vercel-react-best-practices — 34 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/react-best-practices/SKILL.md · 137 lines

How it starts

The opening of the file, as written. The whole thing — 137 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Vercel React Best Practices

Comprehensive performance optimization guide for React and Next.js applications, maintained by Vercel. Contains 57 rules across 8 categories, prioritized by impact to guide automated refactoring and code generation.

When to Apply

Reference these guidelines when:

  • Writing new React components or Next.js pages
  • Implementing data fetching (client or server-side)
  • Reviewing code for performance issues
  • Refactoring existing React/Next.js code
  • Optimizing bundle size or load times

Rule Categories by Priority

Priority Category Impact Prefix
1 Eliminating Waterfalls CRITICAL async-
2 Bundle Size Optimization CRITICAL bundle-
3 Server-Side Performance HIGH server-
4 Client-Side Data Fetching MEDIUM-HIGH client-
5 Re-render Optimization MEDIUM rerender-
6 Rendering Performance MEDIUM rendering-
7 JavaScript Performance LOW-MEDIUM js-
8 Advanced Patterns LOW advanced-

Quick Reference

1. Eliminating Waterfalls (CRITICAL)

  • async-defer-await - Move await into branches where actually used
  • async-parallel - Use Promise.all() for independent operations
  • async-dependencies - Use better-all for partial dependencies
  • async-api-routes - Start promises early, await late in API routes
  • async-suspense-boundaries - Use Suspense to stream content

2. Bundle Size Optimization (CRITICAL)

  • bundle-barrel-imports - Import directly, avoid barrel files
  • bundle-dynamic-imports - Use next/dynamic for heavy components
  • bundle-defer-third-party - Load analytics/logging after hydration
  • bundle-conditional - Load modules only when feature is activated
  • bundle-preload - Preload on hover/focus for perceived speed

3. Server-Side Performance (HIGH)

  • server-auth-actions - Authenticate server actions like API routes
  • server-cache-react - Use React.cache() for per-request deduplication
  • server-cache-lru - Use LRU cache for cross-request caching
  • server-dedup-props - Avoid duplicate serialization in RSC props
  • server-serialization - Minimize data passed to client components
  • server-parallel-fetching - Restructure components to parallelize fetches
  • server-after-nonblocking - Use after() for non-blocking operations

Read the full file on GitHub · 137 lines

Files

What ships with it

60 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 137 lines · 67 tokens per session scan A 61860fd4249c

Subscribe to this mod's changes

vercel-react-best-practices is a skill published in the GitHub repository Atman36/codex-maintainer-kit (2 stars, last pushed 3mo ago), licensed MIT. It adds 67 tokens to every session and 1,499 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 78% identical to vercel-react-best-practices, differing in 34 lines, and is treated as a copy.

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