No single free tool audits a whole website, but three or four of them together come close. Google's own tools tell you what Google sees; a crawler finds technical problems across pages; a browser-based check finds what visitors on phones run into. Limits below were checked on the vendors' sites in October 2026.
The tools
| Tool | Free limit | Best for | Misses |
|---|---|---|---|
| Google Search Console | Free for sites you verify | What Google indexed and why not; real search clicks; Core Web Vitals from real users | Why your site produces the problems; anything Google does not report |
| PageSpeed Insights | One URL per test | Real-user Core Web Vitals and a Lighthouse lab test for a page | Other pages; anything not about speed |
| Lighthouse (in Chrome) | Unlimited, one page at a time | Speed, accessibility and SEO basics while developing | Site-wide problems |
| Screaming Frog SEO Spider | 500 URLs per crawl | Deep technical crawl of a small site | Layout and browser problems; needs installing |
| Ahrefs Free (Webmaster Tools) | 5,000 crawl credits per verified project per month | Technical site audit and backlinks for your own sites | Sites you cannot verify |
| Semrush free account | 100 pages per site audit | A quick technical audit of a small site | Larger sites |
| Bing Webmaster Tools | Free for sites you verify | Bing indexing and a site scan; Bing also feeds Copilot | Google-specific issues |
| SignalCrawler | 3 free scans, up to 50 URLs each | Technical SEO plus browser QA on phone widths, with screenshots and a fix plan | Very large sites; custom crawl configuration |
A free audit routine that covers most problems
- Search Console: open Indexing → Pages and note the reasons with pages you care about. Check Core Web Vitals and Security & manual actions.
- A crawler: run one over the site for broken links, redirects, duplicate titles, canonical and noindex mistakes. Screaming Frog's free version, Ahrefs Free for a verified site, or a SignalCrawler scan.
- PageSpeed Insights: test the homepage and one page of each main type (product, article, category).
- The browser: open key pages at phone width, open the menu, fill a form, try the longest content you have. SignalCrawler automates this step.
- Write it down: a list of problems with the page, what is wrong and who fixes it. A bug report template keeps it in one place.
How to choose
- Your own site, technical depth: Search Console + Ahrefs Free or Screaming Frog.
- Someone else's site (a client, a prospect): tools that do not need verification: Screaming Frog, Semrush free, SignalCrawler.
- A site about to launch: a crawler plus a browser check on staging; Search Console only works once the site is live.
- You need to show the results to non-specialists: a report with screenshots and plain language.
What free tools rarely do
Most free tools stop at listing issues. Deciding which ones matter, grouping them by the template that causes them, and telling a trade-off from a plain bug is the part that takes time. SignalCrawler's report does that for you: findings are grouped by page template, ordered into a plan, and marked when a change needs a team decision or a test first.