Astro JS – the web framework for fast, content-driven websites

Definition

Astro (Astro JS) is a web framework launched in 2021 that ships minimal JavaScript to the browser through islands architecture. It is particularly strong for content-heavy websites where performance and Core Web Vitals are the priority.

What is Astro JS?

Astro (often called Astro JS) is an open-source web framework, launched in 2021, built for content-heavy websites. Astro renders pages to static HTML and ships zero JavaScript to the browser by default – interactive components are loaded only where they are explicitly needed. The architecture is called islands architecture, and it makes Astro websites genuinely fast by default, without the developer having to fight the framework.

The framework was created by Fred Schott, who was previously behind the build tools Snowpack and Skypack, with a clear thesis: most websites are content-heavy, not application-heavy, and should therefore ship as little JavaScript as possible. For blogs, knowledge bases, documentation and marketing pages, Astro is a frequently recommended choice in 2026 – it has quickly grown from challenger to established alternative.

How does Astro work technically?

Astro renders pages on the server at build time (or on demand with an adapter) and sends plain HTML to the browser. Up to this point it is similar to Next.js and Nuxt. The difference lies in how interactive components are handled: in Next.js and Nuxt the whole page is hydrated with JavaScript to make it interactive. Astro ships no JavaScript at all by default – until you explicitly mark a component as interactive. Then only that component (the island) is hydrated, while the rest of the page stays static HTML.

As a result, a typical Astro website delivers considerably less JavaScript than an equivalent Next.js website – Astro's own documentation states that an Astro site can load 40% faster with 90% less JavaScript – which directly improves Core Web Vitals and the time it takes for the page to become interactive.

Is Astro like React? No – Astro is not a component library but a web framework, in the same category as Next.js. Astro is also framework-agnostic: you can mix components from React, Vue, Svelte, Solid, Preact, Lit and Alpine in the same project. Teams with different backgrounds can work in parallel without arguing about frameworks.

Astro vs Next.js – when do you choose which?

Is Astro faster than Next.js? For content-heavy websites: yes, most of the time. That is not because Astro's rendering is faster, but because Astro ships considerably less JavaScript to the browser by default. Less JavaScript means better Core Web Vitals without extra optimisation work. For applications with a lot of client-side logic the difference shrinks – large parts of the page are then hydrated in Astro too.

So the choice comes down to where the website's centre of gravity lies, not which framework is best:

• Choose Astro when content dominates: blog, knowledge base, documentation, marketing pages, programmatic SEO. You get the performance from the start and avoid optimising away JavaScript you never needed.
• Choose Next.js when application logic dominates: logged-in views, dashboards, complex global state, real-time features – or when the team already has a deep React stack and React libraries to reuse.
• Both work for marketing pages with some interactivity. In that case, the team's skills, the existing codebase and the hosting environment matter more than the framework itself.

We build with both frameworks and see them as complementary, not competing.

What is Astro good at?

• Performance by default. Astro ships minimal JavaScript to the browser. For content-heavy websites that translates directly into better Core Web Vitals, better Lighthouse scores and a better experience for real users.
• Content Collections. In our view, one of the best ways to work with markdown and MDX content in a framework: schema validation with Zod, type-safe queries and hot reloading.
• MDX and markdown. First-class support for both. Writing blog posts in markdown and embedding interactive components where needed simplifies the workflow considerably.
• Adapters for different hosting environments. Static export, Vercel, Netlify, Cloudflare, Node, Deno. You are not locked into one platform.
• View Transitions API. By its own account, Astro was the first major web framework with built-in support (Astro 3.0, August 2023), which gives SPA-like page transitions without losing the benefits of SSR.
• Integrations with headless CMS. Solid integrations with Sanity, Contentful, Storyblok, Strapi, Notion and more – often in the form of official starter templates.
• The developer experience. File-based routing, TypeScript by default, fast builds, minimal configuration.

When is Astro not the right choice?

• Heavy client applications. If the website is fundamentally an SPA – a dashboard, a web app, a real-time tool – Astro is not designed for it. Next.js, Nuxt or dedicated SPA frameworks are a better fit.
• Complex state that has to survive navigations. Astro is built around page navigations; if your product has complex global state across pages, there are better choices.
• Heavily personalised content per user. Possible, but it requires SSR and in practice sacrifices some of Astro's static advantages.
• The maturity of the ecosystem. Astro is growing fast, but the ecosystem is younger than React/Next.js or Vue/Nuxt.

How does Astro perform for SEO and Core Web Vitals?

This is where Astro is at its strongest.

• Server-rendered HTML by default. All content is crawlable and present in the initial HTML – no doubt about whether Google can see it.
• Fast pages. Quality content matters most, but all else being equal, Core Web Vitals are a ranking signal for Google. Astro starts from a better baseline than most modern alternatives, which also shows in PageSpeed and Lighthouse measurements.
• Structured data. Easy to add schema markup directly in .astro files or through Content Collections.
• Static export for simple hosting and CDN distribution. Websites with no dynamic requirements can be deployed entirely on a CDN, which means short load times worldwide.
• Image optimisation. Astro's Image component generates optimised formats (AVIF, WebP), a correct srcset and lazy loading by default.
• Programmatic SEO. Content Collections combined with dynamic routes are an excellent foundation for large programmatic SEO projects.

When do we recommend Astro?

Astro is one of our two main options when we build coded websites with a headless CMS – the other is Next.js. We recommend Astro when:

• The website is content-heavy – blog, knowledge base, documentation, marketing pages, programmatic SEO.
• Core Web Vitals are business-critical and your current stack does not deliver.
• You want to be able to mix components from different frameworks, for example during a migration phase.
• You want static builds as an option without being locked into them.

We recommend another framework when the website is fundamentally a heavy interactive application, when the team already has a deep React stack and a migration is not worth the cost, or when the headless CMS you have chosen pairs better with another framework. We describe how we work with coded websites in the guide to AI-assisted web development and on our services page.

Summary

Astro JS is the web framework for content-heavy websites where performance and SEO carry a lot of weight. Islands architecture means minimal JavaScript is shipped to the browser, which directly improves Core Web Vitals and the user experience. The framework-agnostic approach makes Astro useful in many team set-ups, and for blogs, knowledge bases, marketing pages and programmatic SEO it is one of the strongest choices in 2026. For heavy interactive applications, Next.js or a dedicated SPA framework is still the right way to go.