IPvX IP calculator
Originally a demonstration of the IP.pas IP library I created to do IP manipulation (both IPv4 and IPv6) using proper binary IP math (32-bit for IPv4 and 128-bit for IPv6), but reading and writing IP addresses as strings. The algorithms used are detailed in my two-part answer on Network Engineering Stack Exchange. I turned IPvX into a real application. See the IPvX.pdf for a more complete explanation of the application.
Only the IPvX.exe (either IPvX.exe for Win32 or IPvX.exe for Win64]) and the IPvX.chm (help file for either version) are needed to run the application.
IPv4 addresses use the common IPv4 dotted-decimal notation (no leading zeroes in the octets).
IPv6 addresses are accepted in any of the three RFC 4291, Section 2.2. Text Representation of Addresses conventional formats (including expanded, compressed, expanded-mixed, and compressed-mixed in either or both upper- and lower-case), but they are only returned in the RFC 5952, A Recommendation for IPv6 Address Text Representation canonical format (compressed and compressed-mixed for IPv4-mapped IPv6 addresses in only lower-case) because RFC 5952 says:
As IPv6 deployment increases, there will be a dramatic increase in the need to use IPv6 addresses in text. While the IPv6 address architecture in Section 2.2 of RFC 4291 describes a flexible model for text representation of an IPv6 address, this flexibility has been causing problems for operators, system engineers, and users. This document defines a canonical textual representation format. It does not define a format for internal storage, such as within an application or database. It is expected that the canonical format will be followed by humans and systems when representing IPv6 addresses as text, but all implementations must accept and be able to handle any legitimate RFC 4291 format.