Free tools

Most free SEO tools give you a score. A score is a compressed opinion, and it hides the thing you actually needed to see. The tools planned for this site do the opposite: they show the intermediate state — which rule matched, which posting list was read, which header was returned — so you can reason about it yourself.

They are being built one at a time and released when each is genuinely useful. Nothing here is behind an email address.

robots.txt reader

Paste a robots.txt file and a list of URLs, and see which rule matches each URL for each user-agent, including the longest-match precedence that trips people up. It reports what is blocked from fetching, and states clearly that blocking is not deindexing — the single most common misreading, covered in the robots.txt definition.

Structured data preview

Paste JSON-LD and see whether it parses, whether the @id references resolve to nodes that exist, and whether any entity is defined twice. Existing validators check syntax and eligibility; this one checks the graph, which is where hand-built schema usually goes wrong. Background in the structured data definition.

Inverted index demo

Paste a handful of documents and watch the index build term by term, with the posting lists visible and query intersection shown step by step. It is the homepage's worked example, made interactive, and it is the fastest way to see why TF-IDF falls out of the structure naturally.

HTTP header check

Enter a URL and see the exact status code, the full redirect chain, and any X-Robots-Tag header, with no browser cache in between. The equivalent of curl -I for people who would rather not open a terminal, and the ground truth when tools disagree — as the tools guide explains.

In the meantime

The guide to search tools covers what Search Console, Bing Webmaster Tools, server logs, desktop crawlers and rank trackers can each actually prove — which is more useful than any single tool, free or paid.