React is a UI library for building components; Next.js is a full framework built on React that adds routing, server rendering, and SEO out of the box. Use plain React (with Vite) for internal tools and single-page apps that live behind a login; use Next.js for anything public that needs to be found on Google, load fast on first paint, or fetch data on the server.
The real difference, side by side
| Concern | React (e.g. Vite) | Next.js |
|---|---|---|
| Rendering | Client-side by default | Server (SSG / ISR / SSR) — ships complete HTML |
| Routing | Add a router yourself | File-based routing built in |
| SEO | Client-only apps often aren't reliably indexed | Ships crawlable HTML; strong SEO |
| Data fetching | In the browser, after load | Server components fetch close to your data |
| Performance / CWV | You wire up optimization | Image, font, and script optimization built in |
| Best for | Internal tools, SPAs behind a login | Public sites, marketing, SaaS front-ends |
Plain React is enough when
- The app is internal or behind authentication (SEO doesn't matter).
- It's a dashboard or tool where a fast client SPA is fine.
- You don't need server-side data fetching or rendering.
You need Next.js when
- The site is public and must rank in search or AI answers (see the Next.js SEO checklist).
- First-load speed and Core Web Vitals matter (marketing, e-commerce, SaaS).
- You want server-side data fetching and rendering without wiring it up yourself.
The one-question rule
Does this page need to be found and fast? If yes — it's public and SEO/first-load matters — reach for Next.js. If it lives behind a login and speed-to-index is irrelevant, plain React is simpler and perfectly fine.
Our default
We reach for Next.js for public products, marketing sites, and SaaS front-ends where SEO and speed matter, and plain React for internal dashboards and tools behind a login. Which rendering mode to use within Next.js is its own decision — we cover it in SSR vs SSG vs ISR. See our Next.js development service or book a discovery call.