vercel/microfrontends is a library for splitting a large web application into independently developed applications called microfrontends. It supports microfrontend setups using frameworks and tools including Next.js, SvelteKit, React Router, Vite, and React, including gradual migrations and local development.
Borrowing it
Nothing to install: this file belongs to vercel/microfrontends. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/vercel/microfrontends/main/CLAUDE.mdgit clone --depth 1 https://github.com/vercel/microfrontendsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/vercel/microfrontends/claude-md)<a href="https://agentmods.dev/instructions/vercel/microfrontends/claude-md"><img src="https://agentmods.dev/badge/instructions/vercel/microfrontends/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/vercel/microfrontends/claude-md"><img src="https://agentmods.dev/badge/instructions/vercel/microfrontends/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.01094 | $0.01094 |
| Opus 5.5 | $0.00438 | $0.00438 |
| Sonnet 5.5 | $0.00219 | $0.00219 |
| Haiku 4.5 | $0.00109 | $0.00109 |
Grade A, and why
microfrontends CLAUDE.md 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 2mo 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.
This is a copy
100% identical to microfrontends AGENTS.md — 0 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.
How it starts
The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
Project Overview
This is a monorepo for @vercel/microfrontends, a library that enables splitting large applications into independently developed and deployed microfrontends on Vercel. The package provides generic platform support for microfrontends in multiple frameworks, such as Next.js, SvelteKit, React Router, Vite, and React.
Repository Structure
packages/microfrontends/- The main@vercel/microfrontendspackage (the only publishable package)examples/- Working examples of microfrontend implementations (nextjs-app, nextjs-pages, react-router, single-spa, sveltekit, etc.)
Technologies
- This is a TypeScript codebase
- Use pnpm for package management
- Turbo manages the monorepo build pipeline
- The package uses dual ESM/CJS exports via tsup
- Follow Vercel style guide (configured via
@vercel/style-guide) - Be familiar with Module Federation, single-spa, and Next.js Multi-Zones
Common Commands
pnpm build- Build all packages using Turbopnpm test- Run unit tests for all packagespnpm lint- Run ESLint on all packagespnpm format- Format all files with Prettierpnpm typecheck- Run TypeScript type checkingpnpm checks- Run build, lint, test, and typecheck on all packages (run before submitting PRs)
When running commands for a specific application, do not cd into the directory. Run commands from the root. The above commands can be run for a particular package by using a filter option: pnpm checks -F <package name>. Use this.
Make sure that pnpm checks is successful for the entire repository when verifying a change.
Dev examples
pnpm dev:nextjs-app- Run the Next.js App Router examplepnpm dev:nextjs-pages- Run the Next.js Pages Router examplepnpm dev:react-router- Run the React Router examplepnpm dev:single-spa- Run the single-spa examplepnpm dev:sveltekit- Run the SvelteKit example
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.
- 2mo ago First seen · 96 lines · 1,094 tokens per session scan A 0948c91714e1
microfrontends CLAUDE.md is an instructions file published in the GitHub repository vercel/microfrontends (45 stars, last pushed 2d ago), licensed MIT. It adds 1,094 tokens to every session, about $0.0044 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to microfrontends AGENTS.md, differing in 0 lines, and is treated as a copy.
microfrontends CLAUDE.md compared with instructions from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| microfrontends CLAUDE.mdvercel/microfrontends | Instructions file | 45 | 2d ago | MIT | A | 1,094 | Claude Code |
| vscode buildNext.instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 9,719 | GitHub Copilot |
| next.js AGENTS.mdvercel/next.js | Instructions file | 143k | yesterday | MIT | A | 7,461 | Codex, OpenCode |
| langchain AGENTS.mdlangchain-ai/langchain | Instructions file | 149k | yesterday | MIT | A | 4,680 | Codex, OpenCode |
| vscode oss-third-party-notices.instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 5,516 | GitHub Copilot |
| vscode copilot-instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 3,093 | GitHub Copilot |
| deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness | Instructions file | 274k | 2d ago | MIT | A | 4,313 | Codex, OpenCode |