The practice of ensuring JavaScript-rendered content is crawlable, indexable, and ranks well in search engines, addressing the gap between what users see and what crawlers see.
JavaScript SEO is the set of techniques required to make sure JavaScript-heavy sites (single-page apps, React/Vue/Angular applications, progressive web apps) are fully discoverable by search engines. The core problem: traditional HTTP crawlers see the raw HTML response, which for a client-rendered app is often almost empty. The actual content is injected by JavaScript after the page loads.
Google is the only major search engine that consistently renders JavaScript during crawling, using an evergreen Chromium-based renderer. Even so, rendering happens in a second pass that can be delayed by days or weeks, and not every LLM crawler (GPTBot, ClaudeBot, PerplexityBot, OAI-SearchBot) executes JavaScript at all. For AI search visibility, server-rendered HTML is effectively mandatory.
The gap between "works for users in a browser" and "works for search engines" is one of the most common failure modes for modern web apps. A page can render perfectly in Chrome, pass Lighthouse scores, and still be invisible to Google because the crawler sees an empty shell.
The fix is usually server-side rendering (SSR), static site generation (SSG), or prerendering: pre-compute the HTML on the server so that the initial response already contains all the content. Frameworks like Next.js, Nuxt, SvelteKit, Remix, and Astro exist primarily to solve this problem, producing crawler-friendly HTML without sacrificing the interactivity of a JavaScript app.
The Acta AI public site is built on Next.js with App Router, which server-renders every public page by default. The blog, glossary, features, and landing pages all ship fully rendered HTML on the first response, so Googlebot, OpenAI's crawlers, Anthropic's crawlers, and every LLM agent sees the same content a human visitor does.
The easiest way to see whether a page has a JavaScript SEO problem is to disable JavaScript and reload. If the page is blank or missing critical content, crawlers that do not execute JavaScript see the same thing.
# Fetch raw HTML the way a crawler sees it
$ curl -s https://example.com/blog | \
grep -c "<article"
0 # bad: no articles in initial HTML
$ curl -s https://withacta.com/blog | \
grep -c "<article"
12 # good: articles present in initial HTMLA second test is the URL Inspection tool in Google Search Console. It shows both the "crawled HTML" (what Googlebot received) and the "rendered HTML" (what Googlebot saw after running JavaScript). If content only appears in the rendered view, expect slower indexing and missed citations from non-JS crawlers.
Every article on our blog was written by Acta AI. No edits. No ghostwriter.
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