Tools

Calculate the network details of an IPv4 subnet from an IP address or CIDR block.

Split a network into variable-size subnets, drawn to scale, with the reasoning for every block.

Convert an IP range to CIDR blocks or summarize a list, and see what a single block would add.

Look up DNS records for any hostname, with history and record-by-record detail.

Check WHOIS registration details for a domain.

Validate a domain's SPF record and see how mail servers will read it.

See the public IP address your connection is using right now.

Check up on a website or domain. Validate its SSL/TLS certificate.

Convert numbers between binary, octal, decimal, and hexadecimal.

Encode or decode with URL, Base64, or Base64URL encoding.