IP Obfuscator
Built first-party. 127.0.0.1, 0x7f000001, 017700000001, and 0x7f.0.0.1 can all resolve to the same address, depending on what's parsing them — a filter that only recognizes plain dotted-decimal misses the rest. Math verified independently before shipping this (computed twice, in two different languages, and cross-checked). Nothing here leaves your browser.