IPv4 Subnet Mask
Convert a CIDR prefix such as /20 to its dotted subnet mask, or a mask back to its prefix, with wildcard, binary and usable host counts.
Domain and DNS Lookup
5 tools
Which Domain and DNS Lookup tool do you need?
| Tool | What it answers |
|---|---|
| IP Range Calculator | An IP range calculator turns a first and last IPv4 address into an address count and the CIDR blocks that cover it exactly. |
| IPv4 Subnet Mask | A subnet mask marks which bits of an IPv4 address belong to the network. |
| IPv4 to IPv6 Converter | An IPv4 address becomes IPv6 by placing it in the last 32 bits of ::ffff:0:0/96, the IPv4-mapped range from RFC 4291. |
| IPv6 to IPv4 Converter | An IPv6 address only converts to IPv4 when it carries one inside. |
| User Agent Tester | Paste a user-agent string and the tester names the browser, its version, the rendering engine, the operating system and the device type, and flags crawlers. |
All tools
User Agent Tester
Paste a user-agent string to see the browser and version, rendering engine, operating system, device type and whether it claims to be a crawler like Googlebot.
IPv6 to IPv4 Converter
Pull the IPv4 address out of an IPv6 address: ::ffff: mapped, 64:ff9b:: NAT64, 2002:: 6to4 and Teredo forms, one per line, with the address type.
IP Range Calculator
Count the IPv4 addresses between a first and last IP and split the range into the fewest CIDR blocks, e.g. 10.0.0.5–10.0.0.20 needs five prefixes.
IPv4 to IPv6 Converter
Convert an IPv4 address to its IPv4-mapped IPv6 form (::ffff:), the fully expanded address and the 6to4 prefix, with an octet-by-octet hex table.