# Astro

URL: https://softwaredictionary.org/terms/astro
Category: Web Development
Last updated: 2026-10-06
Pronunciation: AS-troh

In short: Astro is a web framework for content-driven sites that renders pages to HTML and ships no JavaScript by default, adding it only to interactive islands.

## What is Astro?

Astro is an open-source framework for websites where most of each page is content to read, such as blogs, documentation, marketing pages and online stores. Pages and components are written in `.astro` files: a script section between `---` fences runs at build time or on the server, and the HTML template below it uses its data. The result is plain HTML and CSS, with no JavaScript sent to the browser unless you ask for it.

Interactivity comes from the islands architecture. A page is a sea of static HTML with a few islands that need JavaScript, such as a search box or an image carousel. You can write those as React, Vue, Svelte, Solid or Preact components, even mixed on one page, and a directive decides when each one loads: `client:load` right away, `client:idle` when the browser is idle, or `client:visible` when it scrolls into view. Astro builds static pages by default and, with an adapter for your host, can also render pages on the server for each request.

Astro reached version 1.0 in 2022 and is built on Vite. In January 2026, The Astro Technology Company, the team behind it, joined Cloudflare; the framework stays open source under the MIT license and still deploys to any host.

Astro is often compared with Next.js. Next.js is a React framework for full web applications and sends React to the browser to run the interface. Astro is content-first, works with several UI frameworks and treats each page as its own HTML document, like a multi-page application, so it ships far less JavaScript on content sites; it is a weaker fit for app-like screens where almost everything is interactive, such as a design tool.

## Key takeaways

- Astro is a framework for content-driven websites such as blogs and documentation.
- Pages render to HTML and ship no JavaScript by default.
- Interactive parts are islands, written in React, Vue, Svelte or others, that load on their own.
- It builds static sites by default and can also render on the server.
- Its company joined Cloudflare in 2026; Astro remains open source under the MIT license.

## Example: An Astro page with a React island

```astro
---
// Runs at build time or on the server, never in the browser
import { getCollection } from "astro:content";
import SearchBox from "../components/SearchBox.jsx";

const posts = await getCollection("blog");
---
<h1>Blog</h1>
<!-- A React island: its JavaScript loads only when it scrolls into view -->
<SearchBox client:visible />
<ul>
  {posts.map((post) => <li><a href={`/blog/${post.id}/`}>{post.data.title}</a></li>)}
</ul>
```

## Frequently asked questions

**Is Astro a static site generator?**

It started as one and still builds static pages by default. With an adapter it can also render pages on the server for each request, so it covers both static and dynamic sites.

**Can I use React with Astro?**

Yes. Astro has official integrations for React, Vue, Svelte, Solid and Preact. Components render to HTML on the server, and only those with a `client:*` directive load their JavaScript in the browser.

**What is the difference between Astro and Next.js?**

Next.js is a React framework for full web applications and sends React to the browser to run the interface. Astro is aimed at content sites, works with several UI frameworks and sends JavaScript only for the interactive islands.

## Sources

- [Astro documentation: Why Astro?](https://docs.astro.build/en/concepts/why-astro/)
- [Astro documentation: Islands architecture](https://docs.astro.build/en/concepts/islands/)

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