SEO Auditor
A live technical and content SEO audit, right in the browser
- Product, SEO judgement and AI-directed development
- October 2026
- Indexability
- On-page
- Content
- Links
- Technical
- Structured data
- Performance
Overview
Crawls up to 25 pages of any public website, runs 70 checks across 7 areas and returns a prioritised list of what to fix first, with evidence and recommendations.
My CV mentioned my own SEO audit tooling; this is the public version, built so anyone can use it.
- checks
- 70
- scored areas
- 7
- pages per crawl, max
- 25
- audit data stored
- 0
Built with Claude as a force multiplier. I defined the checks, thresholds, scoring and security model; tests verify every rule. No LLM is used while auditing: results are deterministic and explainable.
SEO tools say a lot and prioritise little.
Professional suites return hundreds of warnings with the same visual weight. For a small marketing team the real question is different: what do I fix first, and why?
I wanted a tool that answers exactly that, with concrete evidence per URL and an actionable recommendation for every finding.
From domain to action plan in under a minute.
Validation
Public URL, no private IPs
robots.txt
Rules and declared sitemaps
Crawl
BFS, same domain, up to 25 pages
Links
Internal and external, HEAD with GET fallback
Probes
Soft 404 and HTTP → HTTPS redirect
Performance
PageSpeed Insights in parallel
Analysis
70 checks and scoring
What it analyses.
- Indexability
- HTTP status, noindex in meta and header, canonicals (missing, multiple, cross or broken), hreflang with reciprocity, redirect chains, soft 404, robots.txt and sitemaps.
- On-page
- Title in characters and approximate pixel width, meta description, H1 and skipped levels, language, viewport, charset, Open Graph, Twitter Card and favicon.
- Content
- Thin or duplicate content, text/HTML ratio, image alt text, target keyword in title, H1, description and intro, density, n-grams and readability (Fernández-Huerta for Spanish, Flesch for English).
- Links
- Broken internal and external links, links to redirects, empty or generic anchors, internal nofollow and click depth.
- Technical
- HTTPS, HSTS, security headers, mixed content, compression, TTFB, HTML weight, render-blocking resources and images without dimensions.
- Structured data and performance
- JSON-LD validation per schema.org type and lab plus real-user (CrUX) Core Web Vitals via PageSpeed Insights.
Judgement over volume.
- Priority = severity × reach × effort
- An issue that hits every page and takes five minutes to fix rises; a structural improvement on a single URL sinks. The list sorts itself.
- Explainable by design
- Every finding includes why it matters, how to fix it and the affected URLs with the specific data point (length, HTTP code, selector).
- No LLM at runtime
- Rules are deterministic: the same site gives the same result, with no per-audit cost and no made-up answers.
- Streaming
- The server streams progress as NDJSON, so you see which page is being crawled instead of waiting blind.
A public tool that makes requests for you has to be safe.
An auditor that downloads URLs chosen by any visitor is a classic SSRF vector. These are the layers of defence.
validation
http/https only, no credentials in the URL, limited ports and internal hostnames blocked.
DNS
Every connection resolves DNS and rejects private, loopback, link-local, cloud-metadata and reserved IPv6 addresses — after every redirect too (anti DNS rebinding).
limits
Per-request and per-audit timeouts, 3 MB per document, 5 redirects and per-IP rate limiting.
privacy
Nothing is stored: the report lives in your browser and you can export it as JSON or Markdown.
The hard part is deciding what not to flag.
Writing checks is easy; calibrating them is what separates a useful tool from a noisy one. For example, a 403 on an external link is not counted as broken, because many sites block bots without being down.
I reused the SEM Auditor’s logic (explainable rules, severity and priority) and brought it to the web with streaming, unit tests per rule and a security model designed from day one.