Make sure a machine sees what your users see.
Modern frameworks build the page in the browser. Search engines and AI assistants do not always follow. We close the gap between what renders for a user and what a crawler actually receives.
JavaScript SEO is the work of making a site built with client-side frameworks like React, Vue, Angular or Next.js fully crawlable, renderable and indexable. When content, links, canonicals or metadata are injected by JavaScript rather than present in the initial HTML, a crawler can miss them entirely. We diagnose the render gap, decide the right rendering strategy, and make sure the version a machine indexes matches the version a person sees.
JavaScript SEO, in full.
JavaScript SEO exists because of a mismatch most teams never see. A modern framework ships a near-empty HTML shell and builds the real page in the browser after the script runs. A person waits a few hundred milliseconds and gets a full page. A crawler may get the shell, queue the page for rendering later, and in the meantime index almost nothing. The site looks perfect in a browser and performs like a ghost in search, and nobody can explain why because the front end gives no hint that anything is wrong.
Google handles this in two waves. It crawls the raw HTML first, then renders the JavaScript with its Web Rendering Service on a second pass that can lag the first by anything from seconds to days. Whatever your JavaScript injects, body copy, internal links, the canonical tag, the title and meta description, structured data, only counts once that second wave completes and succeeds. If the render times out, hits a script error, or depends on a blocked resource, that content never enters the index. This is why a page can be live, fast and beautiful yet quietly invisible.
The AI layer makes the stakes sharper. The crawlers behind ChatGPT, Perplexity, Claude and the assistant surfaces buyers increasingly trust largely do not execute JavaScript at all. They read the HTML you serve and move on. If your product detail, your pricing, your answer to the question someone asked lives only in the rendered DOM, those systems cannot see it and cannot cite you. Content that depends on a render step is content the fastest-growing discovery channels skip entirely.
None of this means JavaScript is the enemy. React, Vue and Next.js are the right tools for plenty of sites, and a well-built framework site can be flawless for search. The failures come from rendering the wrong things in the wrong place: shipping indexable content client-side, hiding links behind onClick handlers, letting the router return 200s for pages that do not exist. The fix is rarely to rip out the framework. It is to move what search engines and assistants need into HTML they reliably receive, and to prove they receive it.
JavaScript SEO, broken down.
The render gap diagnosis
We fetch each key template as a crawler does and as a browser does, then diff the two. What content, links, canonicals and metadata exist only after JavaScript executes is exactly what is at risk, and it is where every other decision starts.
Explore →Choosing a rendering strategy per template
Client-side, server-side rendering, static generation and dynamic rendering are tools, not doctrines. A marketing page wants pre-rendered HTML; a logged-in dashboard does not need indexing at all. We map the right approach template by template so indexable content is always present without a render step.
JavaScript-injected metadata and canonicals
Titles, descriptions, canonical tags and hreflang written by client-side script are the quietest failure in JavaScript SEO. A crawler acting on the raw HTML sees the wrong canonical or none. We move these signals into the server response where they cannot be missed.
Explore →Routing, internal links and soft 404s
Framework routers navigate without real anchors, and missing pages often return a 200 with an empty shell instead of a 404. We make internal links true crawlable hrefs and make status codes tell the truth, so discovery and index hygiene both hold.
Explore →Structured data after hydration
Schema injected by JavaScript only lands if the render succeeds. For rich results and for machine understanding, we prefer schema served in the initial HTML and validated against what actually renders, not what the code intends.
Explore →Rendering for AI assistants
Because most assistant crawlers never run JavaScript, we treat raw-HTML completeness as a first-class requirement, not an afterthought. If the answer a buyer asks for is in your rendered view only, we bring it into the served HTML so it can be read and cited.
Explore →The way we run JavaScript SEO.
Crawl as a machine, not a browser
We request your templates the way Googlebot and the non-rendering AI crawlers do, capturing the raw HTML they receive before any script executes. That is the ground truth, and it usually differs from what the team has ever looked at.
Diff rendered against raw
We render the same pages and compare, isolating exactly which content, links, canonicals, metadata and schema depend on JavaScript. The diff turns a vague performance worry into a specific, fixable list.
Decide the rendering approach
Template by template, we settle on client-side, server-side, static or dynamic rendering based on how each page needs to be found and indexed, and on what your stack can realistically ship.
Specify or implement the change
We write the fixes into your framework, moving indexable content and signals into the server response, or hand your developers specs precise enough to action without guesswork. We work in Next.js and headless stacks directly.
Verify against live crawl and index
We re-fetch as a crawler, confirm the previously hidden content is now in the raw HTML, and watch Search Console rendering and indexation until the change is proven, not assumed.
Guard against regressions
A single component refactor can push content back behind a render. We monitor the render gap so a future deploy does not quietly re-hide what we just surfaced.
How we approach JavaScript SEO.
Rendered vs raw HTML
We compare what your server sends against what appears after JavaScript runs. If your headings, copy, links or canonical tag only exist in the rendered DOM, that is the gap we close.
The right rendering strategy
Client-side, server-side, static or dynamic rendering each suit different pages. We pick per template based on how it needs to be crawled, not on framework fashion.
Links, routing and soft 404s
Router-driven navigation, JavaScript links and stateful URLs routinely hide pages from crawlers or fake success on missing ones. We make routes real, discoverable and honestly statused.
AI crawlers that do not render
Most AI assistant crawlers fetch your HTML and never execute JavaScript. If your answer lives only in the rendered view, they cannot cite it. We make the content present without a render step.
What JavaScript SEO puts on your desk.
Who does the work, and how
JavaScript SEO sits on the seam between search and engineering, which is exactly where generic SEO advice falls apart. The people diffing your rendered and raw HTML are the same senior practitioners who can read the framework code and write the fix or the spec. There are four of us and no juniors, with roughly forty years of agency experience between us, and we build in Next.js and headless stacks ourselves rather than lobbing recommendations over a wall. We work from what a crawler actually receives, we tell you which render gaps are harmless, and we prove each change against live index behaviour before we call it done.
We read the code and the crawl
Diagnosis rests on fetching your pages as a machine does and on understanding the framework producing them. We do both, so the fix addresses the cause in the template, not the symptom on one page.
We build in these stacks
Because we design and ship Next.js and headless sites, our rendering recommendations are things we implement, not theory. We know what your developers can realistically change and what it costs them.
We verify against the index
A render gap is closed only when the previously hidden content appears in the raw HTML and Search Console confirms it indexed. We check live behaviour rather than trusting that the code should work.
JavaScript SEO: common questions.
What is JavaScript SEO?
It is the practice of making a site built with client-side frameworks fully crawlable, renderable and indexable. When JavaScript generates the content, links, canonicals or metadata rather than the server sending them in HTML, a crawler can miss them. JavaScript SEO closes that gap so search engines and AI assistants index the same page a user sees.
Is JavaScript bad for SEO?
No. React, Vue, Angular and Next.js can all rank perfectly. Problems come from rendering the wrong things in the wrong place, such as shipping indexable content only in the browser, hiding links behind click handlers, or writing canonicals with client-side script. Fix where things render and the framework stops being a liability.
Does Google render JavaScript?
Yes, but on a second pass. Google crawls your raw HTML first, then renders the JavaScript later with its Web Rendering Service, and the gap between the two can be seconds or days. Anything your script injects only counts once that render completes and succeeds. If it times out or errors, that content never enters the index.
Can AI assistants like ChatGPT and Perplexity read JavaScript content?
Mostly not. The crawlers behind the major AI assistants largely fetch your HTML and do not execute JavaScript. If your key content lives only in the rendered DOM, those systems cannot see it and cannot cite you. For AI visibility, the content needs to be present in the HTML you serve, not built in the browser.
How do I know if my site has a JavaScript SEO problem?
The tell is a site that looks flawless in a browser but underperforms in search or is missing from AI answers. The definitive check is to fetch a page as a crawler, before JavaScript runs, and compare it to the rendered version. If your headings, copy, links or canonical only appear after the script executes, you have a render gap worth fixing.
What is the difference between client-side and server-side rendering for SEO?
Client-side rendering sends a near-empty shell and builds the page in the browser, which asks a crawler to do extra work and delays or risks indexing. Server-side rendering, or static generation, sends complete HTML that any crawler reads immediately. For pages you want indexed and cited, serving finished HTML is almost always the safer choice.
Do I need to rebuild my site to fix JavaScript SEO?
Rarely. The usual fix is to move the content and signals search engines need into HTML they reliably receive, template by template, rather than replacing the framework. Where a stack genuinely cannot render server-side, there are pragmatic options, but a full rebuild is the last resort, not the first.
How does JavaScript SEO fit with the rest of technical SEO?
Rendering is one part of the technical foundation, alongside crawl control, indexation, architecture and Core Web Vitals. A render gap caps everything downstream, so we treat it as part of the same diagnosis rather than a bolt-on, and fix it in the same disciplined way we approach the rest of the technical layer.