README.md

May 6, 2026 · View on GitHub

Pareto

Lightweight, streaming-first React SSR framework built on Vite.
A fast, minimal alternative to Next.js, Remix, and TanStack Start.

Documentation · Changelog · Issues

Getting Started

Visit https://paretojs.tech/guides/introduction to get started with Pareto.

Pareto is a lightweight React SSR framework that prioritizes streaming. Built on Vite for instant dev starts, it provides file-based routing, NDJSON streaming for client navigation, per-route head management via React components, and Immer-powered state with automatic SSR hydration.

npx create-pareto my-app
cd my-app && npm install && npm run dev

Performance

Pareto is built for throughput. In CI benchmarks against Next.js, React Router, and TanStack Start on identical hardware (Node 22, Ubuntu, 4 CPUs):

Scenario	Pareto	Next.js	React Router	TanStack Start
Data Loading	2,733/s	293/s	955/s	1,386/s
Streaming SSR	247/s	236/s	247/s	247/s
API / JSON	3,675/s	2,212/s	1,950/s	—
Static SSR	2,224/s	3,328/s	997/s	2,009/s

Under ramp-up load (1→1000 concurrent connections), Pareto sustains the highest QPS before hitting the p99 < 500ms threshold:

Scenario	Pareto	Next.js	React Router	TanStack Start
Data Loading	2,735/s	331/s	1,044/s	1,458/s
Streaming SSR	2,022/s	310/s	807/s	960/s
API / JSON	3,556/s	1,419/s	1,912/s	—

Client JS sent to the browser: 62 KB gzipped (vs Next.js 233 KB, React Router 100 KB, TanStack Start 101 KB).

In practice: a data-loading page serving 2,000 req/s at peak needs 1 Pareto server vs 6 Next.js instances. For streaming SSR, it's 1 vs 7.

Benchmark details: PR #12

Features

Streaming SSR — renderToPipeableStream with defer() for progressive data delivery through Suspense
Vite-powered — Instant dev starts, React Fast Refresh, native ESM in development
File-based routing — page.tsx · layout.tsx · loader.ts · head.tsx · document.tsx · not-found.tsx
Client navigation — SPA-feel <Link> with prefetching, backed by NDJSON streaming
Head management — Per-route head.tsx React components with nested merge and deduplication
State management — Immer-powered defineStore() and defineContextStore() with automatic SSR hydration
TypeScript-first — Full type safety across loaders, pages, and configuration
Security headers — Built-in OWASP baseline middleware

Documentation

Visit paretojs.tech to view the full documentation.

Packages

@paretojs/core — Core framework
create-pareto — Project scaffolding CLI

Community

GitHub Issues — Bug reports and feature requests
GitHub Discussions — Questions and ideas

Contributing

Contributions are welcome. Please open an issue first to discuss what you would like to change.

License

MIT