What this free SEO audit actually checks
Search engines rank what they can crawl, render, and trust. Before they look at your content, they grade the technical surface — how fast pages load, whether the markup is accessible, whether the site declares its structure cleanly, and whether the host enforces HTTPS. This free SEO audit measures all four in a single pass, then layers on the crawlability checks (robots.txt, XML sitemap, HSTS) and a CMS fingerprint so you can see the full technical baseline in under thirty seconds.
The score model is Google's own. Performance, Accessibility, Best Practices, and SEO are pulled from the Lighthouse API — the engine that powers Chrome DevTools and PageSpeed Insights — which means the numbers you see here match what Googlebot itself measures. No proprietary "SEO score" that nobody can verify.
How the audit works, step by step
- Domain normalisation. Stripped of protocol, www, and trailing path so you can paste a URL or a bare domain.
- Lighthouse pass. A headless audit runs the full Lighthouse battery and returns the four category scores.
- Crawlability probes. We fetch
/robots.txt, look for an XML sitemap at the conventional locations, and check the HSTS header on the homepage. - CMS + surface detection. Markup, HTTP headers, and well-known endpoints reveal the CMS, whether a blog exists, and whether the site sells products.
- Server fingerprint. The
Serverresponse header is extracted so you can spot legacy hosting setups at a glance.
Why each signal matters for ranking
- Performance. Google uses Core Web Vitals as a ranking factor. A Performance score under 50 is usually a sign of unoptimised images, render-blocking scripts, or a slow origin server.
- Accessibility. Accessible sites reach more users and the same patterns (semantic HTML, alt text, contrast) help screen readers and search crawlers parse content correctly.
- Best Practices. Covers HTTPS posture, secure browsing APIs, deprecated features, and console errors — a low score here usually flags a maintenance debt.
- SEO. Lighthouse's SEO category checks the on-page basics: meta tags, structured data, viewport, indexability, link text, and mobile-friendliness.
- robots.txt. Missing or misconfigured robots files are one of the top causes of "my pages won't index" tickets. We confirm it exists and is reachable.
- XML sitemap. Sitemaps are how new pages get discovered fast. We probe the standard locations and report whether one is published.
- HSTS / HTTPS. HTTPS is a confirmed ranking signal. HSTS forces it everywhere — its absence is a downgrade-attack risk and a soft negative for search.
When to use this tool
Use it as a smoke test after any release, before you sign a hosting contract, when onboarding a new agency client, or whenever organic traffic drops without an obvious cause. Sales and partnerships teams also use it to qualify inbound leads — a prospect with a missing sitemap and a Performance score of 18 is usually ready for a conversation about marketing infrastructure.
Pair it with the free domain checker for WHOIS and SSL context, the free security scanner for a deeper header audit, and the tech stack checker to see exactly which marketing and analytics tools the site is running. Together they form a complete pre-sales due-diligence kit.
What the scores mean in practice
Lighthouse colour-codes its results: 90+ is green (good), 50–89 is yellow (needs improvement), under 50 is red (poor). A site doesn't need straight 90s to rank — competitive analysis on most B2B verticals shows market leaders sitting between 60 and 85. What matters more is the shape: a Performance of 35 with everything else above 80 means optimise images and scripts. An SEO score of 70 with everything else green usually means a missing meta description, an unhelpful title, or no structured data.
Limits of an automated audit
No automated tool can tell you whether the content actually answers a searcher's question, whether the site's link profile is healthy, or whether the brand has the authority to compete on a given query. Treat this audit as the technical floor — a clean baseline lets your content do the work. If you're seeing red across the board, fix the infrastructure before you invest in content production: the same article on a fast, accessible, crawlable site will outrank a slower competitor running identical copy.
Privacy and rate limits
The audit is anonymous — no account required. We rate-limit usage per browser so the tool stays free for everyone; logged-in LemReveal users get higher limits and can save audit history against accounts in their visitor pipeline. Audits only touch publicly available endpoints; we don't crawl pages behind authentication, and we don't store the audited site's content.