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Punycode Encoder/Decoder

Encode and decode Punycode for internationalized domain names

■ 01

What is Punycode?

Punycode is a way to represent Unicode characters using only the limited ASCII subset (letters, digits, and hyphens) permitted in domain names. It allows internationalized domain names (IDNs) containing non-ASCII charac…

■ 02

How does it work?

The ACE Prefix Punycode-encoded labels are identified by the ASCII Compatible Encoding (ACE) prefix "xn--". For example, the German city "Munchen" becomes "xn--mnchen-3ya" in Punycode. Encoding Process ASCII characters…

■ 03

Sample Cases

Covers German domain, Chinese domain, and Japanese domain so you can compare common inputs and outputs quickly.

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/ Integration

Source code from the selected tool, shown here alongside the live version on the right.

/ Source Code

TypeScript

typescript

// Punycode encoding/decoding for internationalized domains

function toASCII(domain: string): string {
  // Convert each label of the domain
  return domain.split('.').map(label => {
    // If already ASCII, return as-is
    if (/^[\x00-\x7F]*$/.test(label)) {
      return label;
    }
    // Otherwise encode with xn-- prefix