Rendering
What is rendering?
Rendering is the step in which a search engine executes a page’s code, HTML, CSS and JavaScript, to build the page the way a browser shows it. For pages whose content or links are added by JavaScript, rendering is what lets the search engine see that content. Google renders pages using a recent version of Chromium.
Google’s process runs in stages: crawl the raw HTML, queue the page for rendering, render it in a headless browser, then index the rendered result. Rendering takes resources, so it may happen a little after the first crawl. If JavaScript fails, times out or is blocked by robots.txt, Google may index an incomplete page.
How your site is built changes how much rendering matters. With server-side rendering the HTML already contains the content. With client-side rendering the first HTML is mostly empty, and everything depends on the search engine running your JavaScript. Some other crawlers, including many AI crawlers, may not run JavaScript at all.
Why rendering matters for SEO
If key text, links or metadata appear only after JavaScript runs, any rendering failure hides them from search. This is a common cause of single-page apps ranking poorly. See JavaScript SEO.
Rendering also affects what Google sees for layout and mobile usability, and whether lazily loaded content is found.
How to check how Google renders a page
- Open the URL Inspection tool in Search Console, run a live test and view the rendered HTML and screenshot.
- Compare the rendered HTML with what you see in the browser. Missing text or links point to rendering problems.
- Make sure robots.txt doesn’t block the JavaScript and CSS files the page needs.
- Put critical content, links, titles and canonical tags in the server-sent HTML where possible.
Rendering FAQ
Can Google render JavaScript?
Yes. Googlebot uses an evergreen version of Chromium and runs most modern JavaScript. It still helps to keep important content in the initial HTML, because rendering can fail or be delayed.
Do AI crawlers render JavaScript?
Many don’t, or not reliably. If you want AI tools to read your pages, serve the main content in the HTML itself.
Related SEO terms
Crawling is how search engines discover pages: automated bots fetch URLs and follow the links on them to find more pages.
Indexing is when a search engine analyses a crawled page and stores it in its index, so it becomes eligible to appear in search results.
JavaScript SEO is the work of making sure search engines can crawl, render and index content and links that a site builds with JavaScript.
Server-side rendering (SSR) builds a page’s full HTML on the server for each request, so browsers and crawlers get the content in the first response.
Client-side rendering (CSR) sends a near-empty HTML page and builds the content in the browser with JavaScript, which crawlers must run to see it.
Render-blocking resources are CSS and JavaScript files that the browser must download and process before it can show any of the page.