Audit and fix your site’s technical SEO right in your codebase, and make it legible to AI answer engines too. A free, AI-powered SEO checker built on Claude Code that also generates and validates your llms.txt. No crawler, no hosted dashboard, no signup.
/plugin marketplace add sigistry/marketplace/plugin install seo-optimizer@sigistry/seo-optimizer:seo-audit ./srcPowered by the seo-optimizer plugin.
A comprehensive technical SEO audit across ten categories, scored 0–100 with every issue ranked by impact.
Presence, length (50–60 / 120–155 chars), uniqueness, and keyword relevance.
Mobile-first viewport and an early UTF-8 charset declaration.
og:title, description, image, url, and type for rich social sharing.
summary_large_image cards with title, description, and image.
Exactly one H1, no skipped levels, semantic structure.
Descriptive alt text and explicit width/height to protect CLS.
Descriptive anchors, rel="noopener", and crawlable navigation.
Crawlability, sitemap reference, and valid XML.
Self-referencing, absolute, HTTPS canonicals that match og:url.
Schema.org JSON-LD (Article, FAQ, Breadcrumb, Organization…).
Search is no longer only ten blue links. ChatGPT, Claude, Perplexity, and Google AI Overviews read sites too, and they look for signals classic SEO ignores. The checker now covers the layer that decides whether AI systems can use and cite your content.
A curated Markdown map of your site at /llms.txt so AI answer engines and agents can read it. Generated from your real pages when one is missing, validated against the llmstxt.org spec when it exists.
How your robots.txt treats GPTBot, OAI-SearchBot, ClaudeBot, PerplexityBot, and Google-Extended. Reported with the tradeoff, never changed for you.
Server-rendered content, FAQ and HowTo schema, and a clean heading hierarchy so models can extract and cite you instead of skipping past.
/seo-optimizer:llms-audit ./Add the marketplace and the seo-optimizer plugin to Claude Code.
Run /seo-optimizer:seo-audit on a file, a directory, or your framework’s layout. You get a scored report with critical, error, and warning findings.
Apply precise fixes with /seo-optimizer:seo-optimize (or conservative micro-edits with /seo-optimizer:seo-reviewer), or ask the SEO Expert skill.
| Claude SEO Checker | Lighthouse | Ahrefs / Semrush | |
|---|---|---|---|
| Audits your source code | Yes | No (rendered page) | No (crawls live site) |
| Fixes issues for you | Yes | No | No |
| Works before you deploy | Yes | No | No |
| Free, no signup | Yes | Yes | No |
| Framework-aware | Yes | Partial | No |
| AI discoverability (llms.txt) | Yes | No | No |
It is a free, AI-powered SEO audit tool that runs inside Claude Code. You install the seo-optimizer plugin and run /seo-optimizer:seo-audit to scan any HTML file, React, Next.js, or Vue app, or static site for the technical SEO issues that hurt rankings, then fix them with /seo-optimizer:seo-optimize.
Yes. The seo-optimizer plugin is free and open source (MIT). There is no signup, subscription, or hosted dashboard, it runs locally in Claude Code on your own machine.
Title tags and meta descriptions, viewport and charset, Open Graph and Twitter Card tags, heading hierarchy, image alt text, internal and external links, robots.txt and sitemap.xml, canonical URLs, and Schema.org structured data, scored 0–100 and prioritized by impact.
Traditional tools crawl your live, rendered site and hand you a report to act on. The Claude SEO Checker reads your source code (framework layouts, components, templates), catches issues before you deploy, and can apply the fixes for you with /seo-optimizer:seo-optimize instead of just flagging them.
Yes. It is framework-aware and detects React (Create React App, Next.js), Vue (Nuxt), Angular, Svelte (SvelteKit), static site generators (Gatsby, Eleventy, Hugo, Astro), WordPress themes, and plain HTML.
Yes. After the audit, /seo-optimizer:seo-optimize applies precise, minimal edits (and /seo-optimizer:seo-reviewer applies conservative micro-edits under a 5% change limit), so you get fixes as a diff you can review, not a to-do list.
No. Because it runs on your source files, you can audit and fix SEO in a feature branch before anything ships, no live URL or deployment required.
llms.txt is a Markdown file at your site root (the llmstxt.org standard) that gives AI models a curated map of your site so answer engines and agents can read it. Run /seo-optimizer:llms-audit and the plugin validates an existing llms.txt or generates a compliant one from your real pages, plus an optional llms-full.txt that inlines your key content.
Three things decide whether AI answer engines can use your content: a curated llms.txt so they can find your key pages, robots.txt that does not accidentally block AI crawlers (GPTBot, ClaudeBot, PerplexityBot, Google-Extended), and answer-ready structure (server-rendered content with FAQ and HowTo schema). The /seo-optimizer:llms-audit command checks all three and tells you exactly what to fix.
No. Whether to allow or block AI crawlers is a policy decision with real tradeoffs (licensing, cost, privacy), so the checker reports the current state and the tradeoff and leaves the choice to you. It never edits crawler access on its own.