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Punycode / IDN Converter

Encode and decode Punycode for internationalized domain names (IDN). Supports Unicode text to Punycode conversion, IDN domain encoding/decoding with xn-- prefix, and the Bootstring algorithm (RFC 3492). Runs entirely in your browser — your data never leaves your machine.

punycode idn domain unicode internationalization i18n

Published May 30, 2026

All interactive tools run entirely in your browser. Your data never leaves your device.

How It Works

Select a mode (Punycode encode/decode or IDN encode/decode), enter text or a domain name, and see the instant conversion. Uses the Bootstring algorithm specified in RFC 3492 for encoding Unicode characters into ASCII-compatible form.

Modes

  • Punycode Encode: convert Unicode text to Punycode representation
  • Punycode Decode: convert Punycode back to Unicode text
  • IDN Encode: convert Unicode domain to ASCII-compatible encoding (xn— prefix)
  • IDN Decode: convert ACE domain (xn—) back to Unicode

Features

  • RFC 3492 compliant: implements the Bootstring algorithm
  • IDN support: automatic xn— prefix handling for domain labels
  • Per-label analysis: shows which domain labels require ACE encoding
  • Roundtrip safe: encode then decode returns the original text
  • 5 examples: German, Japanese, Chinese, Arabic, and emoji domains
  • Private: runs entirely in the browser — no data transmitted

Use Cases

  • Testing internationalized domain name configurations
  • Converting Unicode domains for DNS registration
  • Debugging IDN-related issues in web applications
  • Understanding how non-ASCII domain names work