Punycode Converter
Developer
Internationalized Domain Names (IDNs) are stored on the wire as ASCII using Punycode (RFC 3492), but humans usually write them in Unicode. This tool converts in both directions, label by label — labels that are already ASCII pass through unchanged, Unicode labels become `xn--…`, and `xn--…` labels become Unicode. Useful for verifying phishing-suspect domains, registering an IDN, or copying a non-ASCII domain into a tool that only accepts ASCII.
ASCII (Punycode)
xn--mnchen-3ya.de
Unicode
münchen.de
Punycode operates per label (the parts between dots). Labels already in ASCII are passed through unchanged.
How to use
- Type or paste a domain in either Unicode or Punycode.
- Read off the ASCII and Unicode equivalents side by side.
- Copy whichever form your tool/registrar needs.
Frequently asked questions
- Why are some letters that look identical encoded differently?
- That's the whole point of Punycode — and the heart of homograph phishing. The Latin `a` (U+0061) and Cyrillic `а` (U+0430) look identical but encode to different ASCII. Pasting a suspect domain into this tool reveals the `xn--…` form, which makes the difference visible.
- Does this validate the domain?
- No — it does the Punycode transformation only. Length limits, IDNA2008 rules about disallowed code points, and TLD policies aren't checked. A converted name might still be rejected by a registrar.
- Why is one of my labels unchanged?
- Punycode only kicks in for labels containing non-ASCII characters. `mail.münchen.de` becomes `mail.xn--mnchen-3ya.de` — only the second label needs encoding.
- Is the conversion lossless both ways?
- Yes — Punycode is a bijective encoding. Encoding then decoding always gets you back to the original (after Unicode normalization). If the round-trip differs, your input had mixed scripts or visual look-alikes that resolved differently.
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