IP Tools
Standalone networking utilities — subnet math, reverse DNS, bulk ASN lookup, IP geolocation, and blocklist checks.
Subnet calculator
CIDR → network/broadcast address, usable host range, subnet & wildcard mask. Fully client-side, no lookup. Also splits a block into smaller subnets.
Reverse DNS (PTR)
Look up the PTR hostname for an IP address.
Bulk IP → ASN lookup
Paste a list of IPs and get prefix, origin ASN, org, and RPKI state for each — export to CSV.
IP geolocation
Country, city, and coordinates (with a map link) for an IP address.
Blocklist / reputation check
Check an IP against Spamhaus, Barracuda, and SORBS DNSBL zones.