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React

React.js | ReactJS

Portrait of Robert Klimant, co-founder of Roelu Studio
Robert KlimantCo-founder

What is React?

React is a JavaScript library for building user interfaces, created by Meta and now used across most of the modern web. React.js works by breaking a screen into small, reusable components — a button, a form, a card — and updating only the parts that change when data changes. It is the foundation under most popular web frameworks, including Next.js.

Why it matters

React won the framework wars a decade ago and the dust has settled. That matters for a buyer because the talent pool is enormous, the ecosystem is mature, and the chance of being stranded on an abandoned stack is near zero. Hiring a React developer in Berlin, Bratislava, or Buenos Aires is straightforward. The libraries you need — analytics, payments, video, auth — all have React integrations on day one. Pick a niche framework and every future hire is harder, every integration is custom work. React is boring tech that keeps the team moving.

How it works

A developer describes what the screen should look like for any given state — logged in, logged out, loading, error — and React handles the actual updates in the browser. When a visitor clicks a button or new data arrives, React figures out the minimum change required and updates only those pixels. The same component library can power a marketing page, a product dashboard, and a mobile app via React Native. Most teams do not use React directly anymore. They use a framework built on top of it — Next.js for full sites, Remix for apps, Astro for content — which adds routing, rendering, and performance defaults on top of React's core model.

Related terms

  • Next.js

    Development

    A modern web framework for building fast, search-friendly websites and apps in React. It is the default choice for serious scale-up sites where speed, SEO, and…

  • Astro

    Development

    A web framework built for content-heavy sites that need to load instantly. It ships almost no JavaScript by default, which is why marketing sites built in…

  • Server-Side Rendering

    Development

    When a website builds the page on the server before sending it to the visitor's browser. The visitor sees finished content immediately, and Google sees the…

  • Component Library

    Design & UX

    A reusable set of pre-built UI pieces — buttons, forms, cards, modals, navigation — that designers and developers pull from instead of building each one fresh…

  • Vercel

    Development

    The hosting and deployment platform built by the same team that builds Next.js. It runs the build pipeline, the global CDN, the preview URLs, and the analytics…

  • Custom Web Development

    Websites

    Building a website from scratch with a designer and developer, instead of using a template or no-code platform — owned by you, shaped to your business, no…

  • Web Application

    Websites

    Software you use through a browser — like Gmail, Figma, or Linear — instead of installing it on your computer. Interactive, account-based, and built around…