Subnets, DNS, latency, certificates.
category
Network
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Subnet Calculator
Compute network, broadcast, usable hosts and masks for any IPv4 CIDR, and type/range/address-count math for IPv6 — shareable via URL.
↗IP Info
Your connection as seen by Cloudflare's edge: public IP, datacenter, latency, TLS and HTTP version.
↗DNS Lookup
Query any record type (A, AAAA, MX, TXT, NS, CNAME, SOA, CAA) for any hostname via DNS-over-HTTPS — shareable via URL.
↗MAC Address Lookup
Identify a MAC address's vendor from the IEEE OUI registry (24/28/36-bit), and see whether it's locally administered or multicast — entirely offline.
↗HTTP Ping
Sample round-trip latency to any URL from your own browser — min/avg/jitter over several requests, no server in between.
↗TLS Certificate Decoder
Decode a PEM certificate entirely in your browser: issuer, subject, validity, public key, SANs, extensions and fingerprints — a hand-written DER/ASN.1 reader, no OpenSSL.
↗IPv6 Subnet Calculator
Plan IPv6 networks: compress or expand any address, split a /48 into /64s with paging, classify address types and get ip6.arpa reverse names — offline, shareable via URL.