Free tools
IP tools, free and without an account.
The everyday network math, in the browser. Nothing is logged and nothing is sent to a server unless the tool needs a lookup.
What is my IP
Your public address as our servers see it, with the full lookup that /api would return for it.
OpenSubnet calculator
Turn an IPv4 or IPv6 CIDR into its network address, broadcast, usable range, host count, netmask and wildcard.
OpenIP to number
Convert an address to the integer behind it, and an integer back to an address. IPv4 and IPv6.
OpenCIDR converter
Cover a start–end address range with the smallest set of CIDR blocks, or expand a CIDR back into its range.
OpenReverse DNS lookup
Find the PTR hostname an address resolves back to, straight from our lookup API.
Open
Need the same data from code? Read the API reference.