Architecture
React vs Astro
React wins for applications with continuous interactivity. Astro wins for content sites, because it ships zero JavaScript by default and hydrates only the components that genuinely need it — which on a marketing site is usually none of them.
Side by side
| Compared on | React (SPA) | Astro |
|---|---|---|
| JavaScript shipped by default | The whole framework | None |
| Best suited to | Applications | Content and marketing sites |
| Interaction cost | Full hydration on every page | Only hydrated islands |
| Content in HTML | Only with SSR or SSG configured | Always |
| Can use React components | Yes | Yes, as islands |
| Learning curve from HTML | Steeper | Gentle |
When React is the right choice
- An application with continuous state and interaction
- A team already fluent in React and shipping product features
- Complex client-side routing with shared state
When Astro is the right choice
- Marketing sites, documentation, blogs and portfolios
- When Core Web Vitals matter and you want them by default
- When you want to use React components without shipping React everywhere
- When the site must be readable with JavaScript disabled
It is not really React versus Astro
Astro can render React components. The real comparison is between shipping a framework runtime to every visitor and shipping it only where interactivity exists. On a content site, the answer is almost always the second.
The measurable difference
This site was a React single-page application before it was rebuilt in Astro. Framework JavaScript on content pages went from 343 KB to zero, and crawlable body text went from 73 words to a full document — the same content, a different delivery decision.
The verdict
React for applications, Astro for content. The framework is not the variable that decides SEO outcomes; whether content exists in the HTML is, and Astro makes that the default rather than a configuration choice.
If you want the full treatment
JavaScript SEO: the difference between what you see and what gets indexed covers this in about 3 minutes — free, ungated, written from client work.
Who wrote this comparison
Anas Bin Masud builds e-commerce sites and does technical SEO for businesses in the UK, Canada and Pakistan. Where a comparison involves something I sell, the page says so — and every comparison here has to name at least two situations where each side wins, because a comparison one option always wins is an advert with a table in it.