Network tools & calculators online

CIDR subnet calculator, HTTP status code reference, and more. Essential tools for networking, API development, and infrastructure work.

// 2tools in this category

cidr calculatornew

subnet math, range, mask, hosts

http statusnew

codes, meanings, common pitfalls

// about

Network tools help developers reason about IP addressing, HTTP protocol semantics, and DNS infrastructure. The CIDR calculator takes any CIDR notation and derives all subnet properties — mask, range, host count, binary representation. The HTTP status reference covers every code from RFC 7231 and later RFCs with practical explanations of when each code should be used.

// common use cases

Calculate the host range of a /27 or /30 subnet for cloud VPC planning
Look up what a 409, 422, or 503 status code means while debugging an API
Verify whether two IP addresses fall in the same subnet before configuring routing
Check the difference between 301 and 302, or 401 and 403

// faq

Why does /24 only give 254 usable hosts?

In any subnet, the first address (all host bits zero) is the network address and the last (all host bits one) is the broadcast address. Neither can be assigned to a host, so a /24 gives 256 − 2 = 254 usable addresses.

What is the difference between 4xx and 5xx errors?

4xx errors indicate a problem with the client request — the client sent something the server cannot or will not process. 5xx errors indicate a server-side failure — the server understood the request but failed to fulfill it.

What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation expresses an IP address and its routing prefix as a single string: the address, a slash, and a prefix length. For example, 192.168.1.0/24 means the first 24 bits are the network part and the remaining 8 bits are the host part.