Punycode converter (IDN converter)

How to use the Punycode converter?

• Place multiple items on multiple lines
• If you enter a whole URL (must properly begin with a protocol name, e.g. http://), the domain name will be Punycode encoded/decoded, the path will be URL encoded or decoded
• The tool uses the IDNA2008 standard, but with Unicode TR#46 Compatibility Processing. Therefore, some conflicting characters are encoded using the old IDNA2003 standard

What is Punycode?

Punycode is a special encoding used to convert Unicode characters to ASCII, which is a smaller, restricted character set. Punycode is used to encode internationalized domain names (IDN). Every Punycode-encoded domain label starts with the xn-- prefix, allowing the DNS to handle non-Latin scripts like Cyrillic, Arabic, or Chinese.

What is an IDN homograph attack?

An IDN homograph attack is a way of deceiving a user by registering a domain name that looks identical to a legitimate one but is actually composed of different Unicode characters. The attacker swaps characters in a well-known domain with visually indistinguishable characters from another script, like Cyrillic. This exploit is made possible by internationalized domain names and the way browsers decode Punycode for display.

What is IDN?

An Internationalized Domain Name (IDN) is a domain name that contains characters beyond the basic a-z, 0-9, and hyphen range. IDN opens domain names to characters from national alphabets: letters with diacritics, Chinese characters, Arabic script, Cyrillic, and hundreds of other scripts supported by Unicode. Under the hood, IDN domains are encoded as Punycode with an xn-- prefix so the DNS can resolve them.