DNS & Email
MX lookup See which mail servers accept mail for a domain, in priority order. DNS lookup Look up any record across several public resolvers and see if a change has propagated. DMARC checker Check the DMARC policy that tells receivers what to do with spoofed mail. DKIM checker Find and validate the DKIM key that signs mail for a domain. SPF checker Validate the SPF record and count its DNS lookups against the limit of 10. CAA checker See which certificate authorities may issue certificates for a domain. MTA-STS checker Check that mail to a domain is always delivered over an encrypted connection. Blacklist checker Find out if a server IP or domain is listed on spam blocklists. Deliverability scan Check SPF, DKIM and DMARC in one pass, with a graded breakdown of what to fix. WHOIS lookup See the registrar, name servers and expiry date of any domain.Performance
Status code checker Follow every redirect and see the status code of each hop. HTTP version checker See which HTTP versions a site speaks: HTTP/1.1, HTTP/2 and HTTP/3. HTTP header checker Inspect the response headers a server sends back. TTFB checker Measure time to first byte, split into DNS, TCP, TLS and server time. Port checker Check whether a port on a server is open and reachable. Ping Measure latency and packet loss to any host, from our servers. Traceroute Follow every router between our servers and a host to spot where latency creeps in. What is my IP? See the public IP address your connection is using right now. What is my user agent? See the user agent your browser sends and what it says about you.Security
HSTS checker Check that a site forces HTTPS and is ready for the preload list. SSL checker Check a certificate, its chain and when it expires. Security headers scanner Grade the security headers a site sends, with a fix for each one. Internet.nl scan Score a site on modern internet standards like IPv6, DNSSEC and HTTPS.SEO
AI website scan See how AI crawlers read a site and what they are allowed to use. Indexability checker Find out if a page can be indexed, and what blocks it if not. robots.txt Tester Test which URLs a robots.txt allows or blocks for each crawler. Sitemap validator Validate an XML sitemap against the sitemaps.org protocol and its limits. OG image preview Preview how a link looks when it is shared on social media.Nothing matches “”
DKIM Record Checker
Look up a domain's DKIM record and check the selector, public key and key strength. Enter the domain and the DKIM selector used to sign its mail.
What is DKIM?
DKIM (DomainKeys Identified Mail) lets a receiving mail server verify that an email was
genuinely sent from your domain and wasn't tampered with in transit. Your mail provider signs
outgoing mail with a private key, and publishes the matching public key in DNS as a TXT record at
selector._domainkey.yourdomain.com.
Where do I find my selector?
The selector is chosen by whoever sends your mail. Common ones include
google (Google Workspace),
selector1 / selector2 (Microsoft 365),
k1 (Mailchimp) and
default. You can also read it from the
s= tag in the DKIM-Signature header of an email you received.