Screaming Frog SEO Spider is the standard desktop crawler for technical SEO, and for large sites and custom crawls it is hard to beat. SignalCrawler is a different kind of tool: it runs in the cloud, tests pages in a real browser the way a tester would, and turns the findings into a plan and a bug list. Many teams use both.
Facts about Screaming Frog below were checked on its website on 11 October 2026.
At a glance
| Screaming Frog SEO Spider | SignalCrawler | |
|---|---|---|
| Where it runs | Desktop app (Windows, macOS, Linux) | In the browser, nothing to install |
| Free use | Up to 500 URLs per crawl | 3 free scans after sign-up, up to 50 URLs each |
| Paid | Annual licence, $279 per user per year | Pay per scan in packages, no subscription (pricing) |
| Crawl size | Unlimited in the paid version, depends on your computer's memory | Up to 500 URLs (standard) or 2,000 URLs (deep scan) |
| Technical SEO checks | Very broad, highly configurable | Broad set of checks with fixed rules |
| Custom extraction, regex, API integrations | Yes | No |
| Tests pages at many screen widths with screenshots | No | Yes, ten widths from 320 px |
| Browser QA (menus, dialogs, forms, longer text, missing images) | No | Yes |
| Speed | PageSpeed Insights integration | Lighthouse on sampled pages and real-user Core Web Vitals |
| Output | Data tables and exports you analyse | Findings with evidence, a prioritised plan, a bug list for developers |
Keep Screaming Frog if
- You crawl sites with tens or hundreds of thousands of URLs.
- You need custom extraction, regex filters, scheduled crawls with your own configuration, or connections to other data.
- You are an SEO specialist who wants the raw data and does the analysis yourself.
Choose SignalCrawler if
- You want to know what is broken and what to do first, not a spreadsheet of every URL.
- You care about how the site works for visitors on phones, not only about crawl data: overflowing layouts, cut-off text, menus that open off screen, forms that fail silently.
- You need something a client, a manager or a developer can read: screenshots, plain explanations, a bug list.
- You do not want to install software or run crawls on your own computer.
- You audit occasionally and prefer paying per scan to an annual licence.
What the free versions give you
Screaming Frog's free version crawls up to 500 URLs; for a small site that covers everything. SignalCrawler's free scans crawl up to 50 URLs and test a few pages in the browser, which is enough to see the kind of findings you would get on a full scan.
Using both
A common split: Screaming Frog for deep technical crawls and data work on large sites, SignalCrawler for regular health checks, pre-launch QA, client reports and the mobile and browser problems a crawler does not see.