All tools

See the A, AAAA, CNAME, MX, TXT, NS, SOA and CAA records for any domain.

Compare your nameservers' answer with what 16 public resolvers return right now.

Find the registrar, key dates, status codes and nameservers of a domain.

Check how many days a domain has left and whether it is locked against transfers.

Find out whether a domain name is already registered, across several extensions.

Find the hostname behind an IP address and check that it points back.

Inspect DNSKEY, parent DS and authenticated-data responses from a validating resolver.

List a domain's mail servers in priority order and check that each one resolves.

Validate an SPF record and count its DNS lookups against the limit of 10.

Fetch a DKIM key by selector and check its format and key length.

Read a DMARC policy in plain English and spot settings that weaken it.

Build an SPF record from the services that send email for your domain.

Create a DMARC record and plan a safe move from monitoring to enforcement.

Paste raw headers to trace each delivery hop and read SPF, DKIM and DMARC results.

Check a certificate's expiry, covered names, chain and supported TLS versions.

Review HSTS, CSP, X-Frame-Options and other headers, with config to fix gaps.

Follow a URL through every redirect and spot loops, HTTP downgrades and long chains.

Check the status code and final destination of up to 20 URLs at once.

See the full response headers a URL sends, with common headers explained.

Read cache directives, validators and CDN cache status for one URL.

See which content encoding a server returns to our HTTP client.

Send an Origin header and inspect cross-origin read permissions.

Test whether a URL is allowed or blocked for Googlebot, AI crawlers and others.

Review a page's title, description, canonical, robots and social sharing tags.

Validate sitemap XML, location fields, duplicates and date syntax.

Build a robots.txt file with common rules, AI crawler options and your sitemap.

Build or explain a cron schedule and see the next run times in your server's time zone.

Create HTTPS, www and page redirect rules for Apache, with the Nginx version alongside.

See the public IP address your connection uses on the internet.

Find the country and network (ASN) behind any IP address.

Check whether a website responds from our server and inspect the response.

Test whether a port on your own connection can be reached from the internet.