1 · See it
The agent view
The answer an agent receives about any domain, rendered for a person: each action’s decision and the reason.
Technical SEO audit: crawl access, sitemap, hosts, links and speed, checked in one scan
In one sentence
A technical SEO audit checks the parts of a site that decide whether crawlers can reach, render and understand its pages — robots.txt, sitemaps, status codes, redirects, hostnames, canonical URLs, internal links, rendering and speed — as opposed to keywords and content. CrawlCheck runs it for free and adds what each named search and AI crawler is actually served.
A technical SEO audit asks one question: can a crawler reach every page you care about, receive the real content and understand what it is? Type a domain and the free scan checks robots.txt, the sitemap and each child file, both hostnames, HTTPS and HSTS, internal links, blocked resources, page weight and speed, then shows what each named search and AI crawler was actually served. A–F grade, fix list in priority order, no signup.
Measured
What the scan measures for this
Robots.txt and sitemap
Every rule resolved for each named crawler, the sitemap and every child it declares, missing lastmod dates, sitemaps that answer HTML or an error, and pages the homepage links to that the sitemap never declares.
Hosts, HTTPS and HSTS
Whether the www and bare hostnames both answer 200 with the same page, how redirects chain, and whether HSTS is sent, preload-eligible or removed.
Internal links
Links on the page that answer an error, redirect, or point at anchors that do not exist.
Rendering and page weight
How much of the page is visible text, whether the content exists before JavaScript runs, and resources robots.txt blocks that the page needs to render.
Core Web Vitals
Field data where Chrome publishes it, a lab reading where it does not, and readings from your own visitors once you add one script.
For agents
What an agent is told about the same site
An agent does not read the report. It asks one endpoint before it reads, cites, connects or transacts, and gets a signed answer built from the same measurement.
2 · Call it
One endpoint
GET /api/v1/resolve?domain= returns the signed answer; preflight returns a decision and a receipt for one action.
3 · Check it
Without trusting us
Every answer is Ed25519-signed and logged; it verifies offline with the published key.
Workflow
The workflow
- Scan the domainAbout thirty read-only requests, about twenty seconds. Nothing is installed and nothing on the site changes.
- Fix in the order givenCrawl access first, then hosts and sitemap, then rendering, then speed. A page no crawler can reach makes every later fix worthless.
- Walk the whole sitePaid plans walk every page the sitemap declares: status, canonical pointing elsewhere, noindex, thin pages, duplicate titles, orphans and undeclared URLs, each named.
- Re-scan to prove itThe second scan is the evidence. A watched domain alerts you when a fixed problem comes back.
Free
Free tools for this
Each one is a single request to the domain you name, answered as text or a download. Put the domain on the end of the URL, or use the form on the tools page.
Test robots.txt for every crawlerWhich group applies to each named crawler, and what it may fetch.Compare with a competitorTwo sites side by side: grades, section gaps and the findings only one of you has.Fail a deploy that breaks crawlingA CI step that blocks a pull request when a scan finds a problem above the severity you set.
Reading
Read next
- XML sitemap audit
- Canonical URL audit: one page, one address
- How to audit internal links and dead anchors
- HSTS audit
Start from what you are checking
llms.txt auditdoes yours resolve, parse and match the site it describes?robots.txt for AI crawlerswhat yours actually permitsEntity map validatordoes your entitymap.json parse, and does every claim in it resolve?SEO audit toolthe technical checks, plus what AI crawlers actually receiveLocal SEO auditdoes your site say who you are, where, and does every listing agree?SEO audit reports for agenciesyour name on the report, the proof still attachedWhat is a website auditWhat is a website audit? What it checks, what it costs, and how to run one freeWhat is an SEO auditWhat is an SEO audit? The checks that matter, in the order to fix themAEO auditcan ChatGPT, Claude, Perplexity and Google reach, read and quote your site?
You cannot pay to improve a score. A licence adds the lists behind the counts and the record over time - never a better grade.
Questions about this page
QWhat does a technical SEO audit check?
Crawl access (robots.txt and status codes), discovery (sitemaps and internal links), duplication (hostnames, redirects and canonical URLs), rendering (whether content exists before JavaScript), security (HTTPS and HSTS) and speed (Core Web Vitals). Each problem should come with the URL and the evidence.
QWhat is the best technical SEO audit tool?
It depends on the job. Screaming Frog SEO Spider is a desktop crawler with deep per-URL control. Semrush Site Audit and Ahrefs Site Audit run scheduled cloud crawls inside a wider SEO suite. CrawlCheck is free, needs no install, and is the one that fetches the page as each named search and AI crawler and compares what each received. CrawlCheck publishes this page.
QHow often should I run a technical SEO audit?
After every release that touches templates, redirects, robots.txt or the CDN, and on a schedule otherwise. Most regressions are caused by a deploy or a security setting, not by content.
QIs the technical SEO audit free?
Yes. The scan, the grade, the full report and the fix list are free with no signup. Paid plans add the whole-site page walk, history and alerts.
QDoes it check Core Web Vitals?
Yes: Chrome field data where it exists, a lab reading where it does not, and first-party readings from your own visitors once you add one script, which covers low-traffic sites Chrome never reports on.