Free online tools

Small, free tools to check domains: look up who registered a domain and when it expires, read its DNS records, find its subdomains in certificate transparency logs or see who owns an IP address. No account, no tracking of your lookups, and every tool is also available to AI assistants through one open MCP server.

• Free whois lookup: check any domain

  Look up who registered a domain, when it expires and which name servers it uses.

  • Registered or available
  • Registrar
  • Creation, update and expiry date
  • Name servers and DNSSEC
  • Domain status flags
  • MCP server for AI assistants

• Free DNS record lookup: check any domain

  Look up the DNS records of a domain: addresses, mail servers, TXT and CAA.

  • A and AAAA addresses with TTL
  • CNAME aliases
  • MX mail servers by priority
  • NS name servers
  • TXT records with SPF and DMARC detection
  • SOA and CAA records
  • MCP server for AI assistants

• Free subdomain finder: discover subdomains of any domain

  Find the subdomains of a domain in certificate transparency logs and DNS.

  • Subdomains from certificate transparency logs
  • Wildcard certificates marked
  • First seen date and last certificate expiry
  • Current and expired names
  • About 120 common names such as www, mail and api checked in DNS
  • Wildcard DNS detection
  • Issuing certificate authorities
  • Copy the full list
  • MCP server for AI assistants

• Free IP lookup: who owns an IP address

  Look up who owns an IP address: network, ASN, organization, country and reverse DNS.

  • Network name, range and CIDR subnet
  • Origin ASN, AS name and BGP prefix
  • Owner organization with address and country
  • Regional internet registry and registration dates
  • Abuse contact
  • Reverse DNS (PTR)
  • IPv4 and IPv6
  • MCP server for AI assistants

Use these tools from an AI assistant (MCP)

Part of the portfolio of Felix Pfeiffer.