Tools

Free domain hygiene checks — ten dossier checks plus context lookups. No signup. Also callable over MCP.

Want all ten in one shareable report? Run the domain dossier →

DNS

dns records lookup
resolve A, AAAA, NS, SOA, CAA, and TXT records for a domain in one go.
mx lookup
list the mail exchangers (MX records) a domain advertises, sorted by priority.

Email auth

spf checker
find and parse a domain's SPF (sender policy framework) record.
dmarc checker
find and parse a domain's DMARC policy record at _dmarc.<domain>.
dkim lookup
probe common DKIM selectors (default, google, k1, selector1/2, mxvault) for a domain.

Transport

tls certificate checker
inspect a domain's TLS certificate: subject, issuer, validity, SANs, fingerprint.
redirect checker
trace the HTTP(S) redirect chain from https://<domain>/ up to 10 hops.

Web security

security headers checker
inspect the response headers served at https://<domain>/ — HSTS, CSP, X-Frame-Options, etc.
cors checker
run a CORS preflight (OPTIONS) against a domain and surface the access-control-* response headers.
web surface inspector
fetch robots.txt, sitemap.xml, and the home page's <head> to summarise a domain's public-web surface.

Domain context

Auxiliary lookups for geolocation, request fingerprinting, and single-record DNS — not part of the dossier engine, but useful when investigating a finding.

user agent
parse your browser's user agent string (browser, os, device, engine).
what is my ip
your public ip address, location, and timezone.
http headers
inspect the http request headers your browser sends.
ip lookup
look up any IP's geolocation, ASN, and ISP (via ipinfo.io).
dns lookup
resolve A, AAAA, MX, TXT, NS, or CNAME records via Cloudflare DoH.