Content and links only pay off once the technical foundation is sound: the site has to be crawlable, fast, and cleanly indexed. These two tools cover the two halves of that job — crawling and structure on one side, page speed and experience on the other — and most technical work starts by running both.
The tools
Screaming Frog SEO Spider
Screaming Frog is a desktop crawler that walks a website the way a search engine does, following links and cataloguing every URL, title, meta description, heading, redirect, status code and canonical it finds. It is the fastest way to surface technical problems at scale — broken links, redirect chains, duplicate titles, missing metadata, orphaned pages, malformed structured data — on sites from a few pages to hundreds of thousands. Because it runs locally and connects to the GA4, Search Console and PageSpeed APIs, you can blend crawl data with real performance and traffic data in one export. It has a learning curve, but it is the single most useful tool in a technical SEO's kit.
PageSpeed Insights
PageSpeed Insights (PSI) is Google's free tool for scoring how fast a page loads and how it performs against Core Web Vitals — LCP, INP and CLS. It combines lab data from Lighthouse, which is a controlled test you can run on demand, with real-world field data from the Chrome User Experience Report, which reflects how actual visitors experience the page. That distinction matters: the lab score is a diagnostic, but the field data is closer to what Google actually uses for the page-experience signal. Run it on your key templates rather than one page, since performance usually varies by template, not by individual URL.
How to choose
These are not competitors — they do different halves of the job, so use both. Screaming Frog to crawl the site and diagnose structure, indexation and on-page issues; PageSpeed Insights to check speed and Core Web Vitals on the templates that matter. Fix structure first, then chase performance, because a fast page that cannot be crawled still will not rank.
