Punycode Converter

Domain names travel as Latin letters, digits, and hyphens. A Cyrillic name is written as a string like xn--80aswg.xn--p1ai: that is how mail programs, registries, and services that do not understand national letters see the address сайт.рф.

The tool converts the address as a whole: the scheme, path, parameters, and anchor stay in place, and Cyrillic in the path is encoded by the URL rules. For email addresses, only the domain part is converted.

A name splits at the dots into labels, and each label has its own limit: one label is at most 63 characters, and the full name with dots is at most 253. The address магазин.пример.рф has three labels, and the 63-character limit applies to each of them separately. These rules come from the domain name system itself and do not depend on the registrar.

Conversion makes the string longer: the xn-- prefix is added plus a few extra characters, and how many depends on the letters themselves. "Делопроизводство", 16 letters, produces 23 characters; "интернет-магазин", also 16, already produces 26. So a single label fits roughly 43 Cyrillic letters rather than 63, and you can only see that after conversion: in Cyrillic the name looks perfectly ordinary.

The alphabet is checked separately. The string "сбербaнк" with a Latin "a" looks genuine but leads somewhere else: to the system this is a different domain. The tool warns about such addresses and names the substituted letters.

Up to 1000 lines are processed in one run.