Guides · 2026-10-03 · By VSNARY | Emmanuel Orta · 0 views

Screaming Frog vs Sitebulb vs CrawlCheck for AI crawler audits

Two deep technical crawlers and one AI crawler audit, compared on what each fetches, which identities it tests, robots.txt handling and price, with where CrawlCheck falls short.

Screaming Frog and Sitebulb are the two desktop crawlers most SEO teams already own, so the first question about AI crawlers is usually whether they can do the job. They can do part of it. Both crawl a whole site deeply, render JavaScript and report on-page problems at a scale CrawlCheck does not attempt. What neither is built to do is fetch the same site as several identities at once (a browser, GPTBot, OAI-SearchBot, ClaudeBot, Claude-SearchBot, PerplexityBot, Googlebot and others) and compare what each one was served. That comparison is how you find the site that serves browsers and refuses AI crawlers.

Disclosure: CrawlCheck publishes this comparison and is one of the products in it. Every figure about another company comes from that company’s own pricing or documentation page, linked where it appears, read on 3 October 2026. Where CrawlCheck does less than a competitor, the tables say so.

Side by side #

Sources: Screaming Frog pricing and configuration guide; Sitebulb pricing; CrawlCheck pricing.

Can I just set Screaming Frog’s user-agent to GPTBot? #

You can, and it is a useful test. Screaming Frog lets you enter a custom user-agent string, so a crawl with GPTBot’s string shows what your server returns to that name. Three things limit what it proves. It tests one identity per crawl, so comparing GPTBot with a browser means two crawls and a manual diff. It runs from your own IP address, which your CDN may trust differently from a data centre. And many bot-management rules key on more than the user-agent string. Use it as a spot check; it does not replace a side-by-side comparison of every identity.

What only the AI crawler comparison finds #

Each of these depends on comparing identities or reading robots.txt per crawler. A single-identity crawl, however deep, reports the site as fine.

Turning one finding into a site-wide list #

The three tools work best in sequence. CrawlCheck finds the problem from the outside, on the pages an AI crawler reaches first; the desktop crawler then finds every page that shares the cause. The most common case is content that only exists after JavaScript runs, found on 1.1% of scanned sites:

1. The CrawlCheck report flags the homepage: the HTML a crawler receives carries little of the text a browser shows.
2. In Screaming Frog, enable JavaScript rendering and check the Contains JavaScript Content issue, which lists pages whose rendered text differs from the original HTML. In Sitebulb, the Response vs Render report makes the same comparison.
3. Group the affected pages by template; the fix is usually one change to the template or the rendering setup, not page-by-page edits.
4. Rescan with CrawlCheck to confirm AI crawlers now receive the text.

Why one identity per crawl misses access problems #

Access failures are differences: the same URL answered one way for a browser and another way for GPTBot. A crawl that uses a single identity sees one side of the difference and has nothing to compare it with. A 200 with a full page for Googlebot looks healthy in a desktop audit even when ClaudeBot receives a 403 from the same server a second later. Finding that needs both fetches, close together in time, and a comparison of status, size and content between them, repeated for each crawler that matters to you.

The robots.txt side works the same way. A file can allow Googlebot everything and, through a named group further down, drop every rule for GPTBot. Reading the file as one crawler shows one group. CrawlCheck resolves it for each of 114 user-agents and reports where the groups disagree with the intent of the file.

Cost per question #

• Full technical audit of a large site: a desktop crawler licence, priced in the table above, is the cost-effective tool.
• Are AI crawlers served the site: a free CrawlCheck scan answers it for the homepage and machine files.
• Is it still true next week: CrawlCheck Watch re-measures twice a day for $29 a month across three domains.

Where CrawlCheck is weaker #

For classic technical SEO, Screaming Frog and Sitebulb do far more: full-site link graphs, redirect chains across thousands of URLs, duplicate titles, structured data across every template, custom extraction, and visualisations. CrawlCheck’s free scan reads one homepage and the machine files around it; its deep crawl tops out at 500 or 5,000 pages depending on plan. If you need a 100,000-URL audit, buy one of them. If you need to know whether ChatGPT, Claude and Perplexity are being served your site, add CrawlCheck.

Recommended setup #

• Keep your desktop crawler for site-wide technical SEO.
• Run a free CrawlCheck scan for the AI crawler comparison and the robots.txt resolution per crawler.
• When a CrawlCheck finding points at a template (for example JavaScript-only content), use the desktop crawler to find every page on that template.

Related: what each SEO audit tool actually fetches and the crawler delivery comparison.

Questions this post answers

Can Screaming Frog check if AI crawlers can read my site?

Partly. Screaming Frog lets you set a custom user-agent such as GPTBot's and crawl as that name, one identity per crawl, from your own IP address. It does not compare several AI crawler identities against a browser in one pass or resolve robots.txt for every AI crawler. CrawlCheck does that comparison in one free scan.

Screaming Frog vs Sitebulb: which is better?

Both are mature technical SEO crawlers that render JavaScript. Screaming Frog costs $279 a year with a free 500-URL version; Sitebulb offers desktop plans and a cloud plan from £95 a month with a 14-day free trial. The better choice depends on workflow; neither is built to compare what AI crawlers are served.

How is CrawlCheck different from Screaming Frog?

Screaming Frog crawls a whole site deeply as one identity. CrawlCheck fetches a site as several identities, including GPTBot, ClaudeBot and PerplexityBot, and compares what each was served, then resolves robots.txt for 114 user-agents. It reads far fewer pages, so it complements rather than replaces a desktop crawler.

How much does Screaming Frog cost?

$279 per year per licence according to Screaming Frog's pricing page on 3 October 2026, with volume discounts from five licences. The free version crawls up to 500 URLs.

Do I need both a desktop crawler and CrawlCheck?

For most sites, yes. A desktop crawler covers site-wide technical SEO at scale; CrawlCheck covers whether AI crawlers are allowed, served and able to quote the site. CrawlCheck scans are free.

Related findings

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