Speed and SEO.
One test. One fix plan.
Lighthouse performance tests with waterfalls and filmstrips, a full SEO + AI-readiness audit, scheduled monitoring with alerts — and AI-generated fix plans that tell you exactly what to change, in what order.
Free plan: unlimited basic tests (5/hour, 25/day), with API and MCP access. No credit card.
GTmetrix-class speed tests
Core Web Vitals, request waterfall, filmstrip, structure audits, letter grades — everything you expect, on desktop or mobile with connection throttling.
SEO + AI-readiness audit
A crawler checks titles, meta, broken links, canonicals, structured data, sitemap, robots.txt — plus AEO/GEO checks so AI assistants can find and cite your site.
Built for AI assistants
The first performance tool with a native MCP server. Connect Claude or any MCP client and ask it to test your site, watch vitals history, and pull the fix plan.
Free SEO tools — no signup
Need one answer rather than a full audit? Each of these runs on its own, in the browser, with no account:
Meta Tag Checker
Test your title, meta description, Open Graph and robots tags against SEO best practice.
Robots.txt Tester
Parse any robots.txt and test whether a specific path is allowed or blocked for a crawler.
XML Sitemap Checker
Validate sitemap.xml, count URLs and sample-check that listed pages actually resolve.
Redirect Checker
Trace the full redirect chain hop by hop — spot loops, long chains and HTTPS downgrades.
Broken Link Checker
Scan a page for internal links that return 404s or server errors.
Core Web Vitals Checker
Real-user LCP, INP and CLS from the Chrome UX Report — mobile and desktop side by side.
Structured Data Validator
Validate every JSON-LD block on a page, list schema types and catch parse errors.
llms.txt Generator
Generate a spec-compliant llms.txt file that points AI assistants at your key pages.
AI Crawler Access Checker
See whether GPTBot, ClaudeBot, PerplexityBot and Google-Extended are allowed to read your page.
SSL Certificate Checker
Read a site’s TLS certificate: issuer, expiry, days remaining and hostname coverage.
Page Weight Analyzer
Measure how heavy a page is — HTML, scripts, stylesheets and images, byte by byte.
Core Web Vitals guides by platform
Platform-specific fixes for the things that actually break LCP, INP and CLS on your stack:
From the blog
- What actually breaks Core Web Vitals in 2026 — and how to find it
The six failure classes behind most bad LCP, TBT and CLS scores — how each one shows up, the exact fix with code, and which audit catches it.
- We built an MCP server so AI agents can run speed tests — here's how
Streamable HTTP with a stateless server, sha256-hashed API keys, and Postgres as the queue — the architecture behind our MCP server.
- How we run a GTmetrix-class testing stack on one small VPS
Postgres as the job queue after we deleted Redis, one Chrome at a time inside a 2 GB container, HAR files rebuilt from the DevTools log, and a deploy that is a tarball over SSH. The whole architecture, honestly.
- What 60 real Lighthouse runs say about what actually breaks LCP
We ran our own test engine against the 60 most-visited sites that will answer a mobile browser. The audits everyone fixes fail on fast sites too — here is what actually separates a 2-second LCP from a 5-second one.
- We audited 12 framework starter templates. 11 ship zero structured data.
We ran our 41-check SEO/AEO crawler over the official Next.js, Astro, SvelteKit and Nuxt starters — 85 pages. Full scores, the three checks almost everything fails, and the methodology.