Best Rendering Tools for SEO Audits: Raw vs Rendered HTML

The best rendering tool for an SEO audit is one that can crawl your site twice, once as raw HTML and once rendered in a headless browser, and show you the difference, because the difference is what a non-rendering crawler misses. Screaming Frog, Sitebulb, Semrush (Guru and up), Ahrefs, SE Ranking, Lumar, Oncrawl and bseoa all render JavaScript; they differ in what rendering costs you, which plans include it, and whether they compare raw and rendered output for you. Google’s URL Inspection live test is the free check for a single page.

Vendor facts below were checked on 31 October 2026 on the pages linked, except where noted.

Why does rendered vs raw HTML matter for an audit?

Google processes JavaScript pages in three phases, crawling, rendering and indexing, and its JavaScript SEO basics guide says pages “may stay on this queue for a few seconds, but it can take longer than that” before a headless Chromium renders them. The same guide says “server-side or pre-rendering is still a great idea” because “not all bots can run JavaScript.”

That second point is the one most audits skip. Googlebot renders. Most AI crawlers and many other bots take the HTML your server sent and stop there. A page whose links, headings or body text are injected by JavaScript can look fine in a rendered crawl and nearly empty to everything else. Can AI crawlers see JavaScript content? goes into which bots render and which don’t.

So an audit of a JavaScript site needs both views:

Raw HTML crawl: what the server sends. Fast. Shows what non-rendering bots see.
Rendered crawl: what a browser builds. Slow. Shows what Google eventually sees and what users see.
The gap between them: content, links and structured data that only exist after JavaScript runs.

Which SEO tools render JavaScript, and what does it cost?

Tool	Runs	Renders JavaScript	What rendering costs	Source
Screaming Frog SEO Spider	Desktop	Yes, paid license	Included in $279/year license	user guide, pricing
Sitebulb	Desktop or cloud	Yes, all plans	“No extra cost for JavaScript crawling”	pricing
Semrush Site Audit	Cloud	Guru and Business toolkits only	Higher plan	KB: configuring Site Audit
Ahrefs Site Audit	Cloud	Yes, “Execute JavaScript” toggle	Credits are per 200 OK HTML page; no extra rendering charge documented	settings help, credits help
SE Ranking Website Audit	Cloud	Yes, in the audit wizard or Parser Settings	Not documented; crawls take longer	SE Ranking blog
Lumar	Cloud	Yes, “Enable JavaScript rendering”	Quote only	product guide
Oncrawl	Cloud	Yes	3 crawl tokens per URL instead of 1	help center
bseoa	Desktop and CLI	Yes, headless Chrome with `--spa`	Included; no page limit	features
Google URL Inspection	Web (Search Console)	Live test shows a screenshot, HTML and console output	Free, one URL at a time, daily limits	Google help

All checked on 31 October 2026. Sitebulb’s pricing page didn’t show plan prices when I fetched it; its rendering terms and URL limits (Lite 10,000 URLs per audit, Pro 500,000) are from that day. Lumar’s rendering guide dates from 2020, and the current interface may differ.

What should a rendering crawler tell you?

Turning rendering on is the easy part. The useful question is what the tool does with two versions of each page.

Semrush has a JS Impact report that its help center describes as showing your site before and after JavaScript renders, including what content changed.
Lumar calculates rendering issue metrics only when rendering is on, per its product guide.
Oncrawl suggests running the crawl with and without JavaScript and comparing the two yourself.
bseoa, in --spa mode, keeps the server’s HTML and the rendered DOM for each page and reports the gap: text, headings, links or structured data that only exist after JavaScript runs. Those are published as warnings such as Your Links Are Added by JavaScript and Most of Your Page Text Only Exists After JavaScript Runs. Without --spa, it still flags pages that look like an empty app shell from the raw HTML alone.

A tool that only shows you the rendered result tells you what Google eventually sees. A tool that shows the difference tells you what to fix.

How do you run a rendering audit without wasting crawl budget?

Crawl raw first. It’s fast and cheap on every tool. Note the page count and internal link count.
Render a sample. Pick one template of each type (home, category, product, article) and test it with Google’s URL Inspection live test. If the screenshot and HTML match what users see, rendering works for Google.
Render the full site if the sample differs. On Oncrawl that triples the token cost; on Semrush it needs the higher plan. Budget for it before you start.
Compare counts. If the rendered crawl finds many more pages or links than the raw one, your navigation depends on JavaScript. That’s the finding.

With bseoa the rendered crawl is one flag:

black-seo-analyzer \
  --url-to-begin-crawl https://example.com \
  --spa \
  --output-type json \
  --output-file rendered.json

Which rendering tool should you use?

Situation	Good fit
One page, free, as Google sees it	URL Inspection live test
Already on Semrush Guru or higher	Semrush, with the JS Impact report
Already on Ahrefs	Ahrefs with Execute JavaScript on
Large site, log data alongside rendering	Oncrawl or Lumar
Desktop crawler, rendering included, annual license	Screaming Frog or Sitebulb
Desktop or CLI crawler, rendering included, one-time price, raw vs rendered gap reported	bseoa

bseoa is the one I build: a desktop GUI and CLI for Windows, macOS and Linux, $279 once, with a 14-day trial that has every feature and no page limit. Its hosted connector for Claude and ChatGPT doesn’t render JavaScript, so run rendered crawls from the desktop app or the CLI.

Best Rendering Tools for SEO Audits: Rendered vs Raw HTML Crawlers Compared