A single page application (SPA) is a web app that loads one HTML page and then updates the visible content using JavaScript as the user interacts. The page never performs a full reload, with navigation handled on the client side by a framework such as React or Vue.
Also called: SPA
Why it matters
Clients benefit from an SPA because the interface feels faster and smoother, keeping visitors on the site longer and reducing the number of server requests that cost money. A fluid experience can improve conversion rates and lower hosting bandwidth usage.
How it works
When the browser first loads the SPA it receives a minimal HTML skeleton plus a bundled JavaScript file; that script registers routes with the History API, intercepts link clicks, and fetches data via XHR or the Fetch API. The framework then renders components into the DOM, updating only the parts that change, while the server typically supplies JSON responses instead of full pages.
The mistake people make
A common error is assuming an SPA will be indexed by search engines without extra work; crawlers that do not execute JavaScript will see only the initial skeleton, resulting in poor SEO and missing content in search results. The remedy is to add server‑side rendering or pre‑rendering for critical pages.
Related terms
react, client-side routing, progressive web app, server-side rendering
