SEO Tools

Tools for SEO auditing, structured data validation, performance testing, and keyword/backlink research.

Ahrefs — commercial SEO platform built on its own crawler and web index (AhrefsBot, ~170T pages, 41.9B keywords across 217+ countries), covering backlink and competitor analysis (Site Explorer), keyword research, rank tracking, site audits, and content/link prospecting (Content Explorer); Brand Radar tracks brand mentions in AI search answers
Semrush — commercial all-in-one marketing platform combining keyword research (28B keyword database across 142 geographic databases), backlink analysis (43T backlinks), site audits, rank tracking, and competitor traffic analytics; its AI Visibility toolkit tracks how often a brand is cited in LLM answers and compares that share against competitors
OpenSEO — open-source (MIT) alternative to Semrush/Ahrefs for keyword research, backlink analysis, rank tracking, competitor insights, and AI visibility; self-hostable via Docker or Cloudflare, or use the managed version at app.openseo.so; requires bringing your own DataForSEO API key

Lighthouse — Google’s open-source page audit (performance, a11y, SEO, PWA); run via npx lighthouse <url> --view
sitespeed.io — open-source suite for measuring web performance and Core Web Vitals; runs in Docker or via npm, integrates with Grafana/Graphite/InfluxDB for continuous monitoring; includes Browsertime (browser automation and timing), Coach (recommendations), and PageXray (page composition analysis)
WebPageTest — detailed performance tests from real browsers across global locations; waterfall, filmstrip, and Core Web Vitals
GTmetrix — performance reports combining Lighthouse scores with waterfall and historical tracking