What an SEO Tool Actually Does

Ask what an SEO tool actually does — or what belongs in an SEO toolbox — and you'll get a sales page. Here's the plain version: SEO tools do four jobs, most sites need two of them, and the essential ones are free.

The four jobs SEO tools do

• Crawling — fetch every page on a site and report what's broken: missing titles, redirect chains, duplicate content, orphan pages.
• Keyword data — estimate search volume, difficulty, and related terms.
• Backlink analysis — show which sites link to you or a competitor.
• Rank tracking — a ranking tool monitors position changes for specific queries over time.

Almost every paid tool is some combination of these four. The differences are database size and interface, not capability.

The best SEO tools for beginner marketers (all free)

If you're starting out, these cover the majority of real work:

• Google Search Console — indexing status, crawl errors, Core Web Vitals, and the actual queries bringing people to your site. This is the single most valuable tool in SEO and it costs nothing. Nothing else gives you real data about your site.
• PageSpeed Insights — Core Web Vitals with specific, prioritised fixes.
• Rich Results Test — validates structured data.
• Bing Webmaster Tools — free, and surfaces some data Google doesn't.
• Screaming Frog — free tier crawls up to 500 URLs. Enough for most small sites.

Best open source SEO tools

Genuinely open source options are thinner on the ground than marketing pages suggest, but a few are worth knowing:

• Lighthouse — Google's open source auditing engine, built into Chrome DevTools. Performance, SEO, and accessibility scoring you can run locally or in CI.
• web-vitals — Google's open source library for measuring Core Web Vitals from real users on your own site.
• Your browser's View Source — free, instant, and shows exactly what a non-JavaScript crawler sees. Underrated.

When paid tools become worth it

Two situations: competitor research and backlink analysis. Search Console shows your data only — it can't tell you what a competitor ranks for or who links to them. That's the genuine gap Semrush and Ahrefs fill.

For a new site with little traffic and no competitors worth analysing yet, a subscription is usually premature. The free stack above does more than most people use it for.

Related: which metrics to actually watch and how to run an audit with these tools.