Punycode / IDN Converter

Punycode and IDN Converter Online

This service converts internationalized domain names (IDN) — Cyrillic, Chinese, Arabic and others — to Punycode (ACE, ASCII Compatible Encoding) format and back. Uses the IDNA2008 (UTS#46) standard.

What is Punycode

Punycode is an algorithm for encoding Unicode strings into ASCII for use in DNS. Domains like пример.рф are converted to xn--e1afmapc.xn--p1acf, which are handled by standard DNS servers.

Use Cases

• Converting IDN domains with non-Latin scripts to ASCII-compatible format;
• Verifying Punycode correctness when configuring DNS;
• Protection against phishing — homograph attacks use similar characters from different alphabets;
• Debugging mail servers and certificates for IDN domains.

Frequently Asked Questions

• What should I do if my .рф domain fails to convert and shows an error?

  There are two likely causes: either the domain contains characters not permitted by the IDN standard (such as underscores or spaces), or one of the labels exceeds 63 characters after encoding. Try removing any disallowed characters and use only letters, digits, and hyphens in the correct positions. The converter will display a specific error message if one occurs.

• How do I convert Punycode back to a readable Cyrillic domain?

  Simply paste the ACE-encoded string (beginning with xn--), for example xn--e1afmkfd.xn--p1ai, into the converter input and click the convert button. The tool automatically detects the direction and displays the original domain name, such as пример.рф. Reverse conversion is free and takes a fraction of a second.

• Does the Punycode converter support domains with the letter "ё" or other rare Cyrillic characters?

  Yes, the IDN UTS46 standard used by this tool supports all letters of the Russian alphabet, including "ё". Note that "ё" and "е" are distinct Unicode characters, so domains containing them will result in different Punycode strings. The converter correctly handles any valid Unicode character that is permitted by the IDN specification.