Punycode & IDN Converter
Convert internationalised domain names between Unicode and Punycode (xn--), in both directions, as you type.
Label breakdown
| Label | Becomes | Action |
|---|
How it works
Type an internationalised domain name and this converter rewrites it label by label
using the Punycode bootstring algorithm from RFC 3492, the encoding
IDNA uses to squeeze Unicode domains into the ASCII letters, digits and hyphens that
DNS actually accepts. Unicode labels come out prefixed with xn--
(mรผnchen.de becomes xn--mnchen-3ya.de), and any label that
already starts with xn-- is decoded back to the readable form. Auto-detect
handles both directions in one paste, including mixed input where only some labels are
encoded. Full URLs and email addresses work too: only the host part is converted, so
the scheme, port, path, query and mailbox name are copied through untouched.
Before encoding, each label is Unicode-normalised to NFC, lower-cased, and the
full-width and ideographic dot separators (๏ผ, ใ,
๏ฝก) are mapped to a plain .. That covers the common cases but
it is not the complete UTS-46 mapping table, and this tool does not enforce
IDNA2008 script or bidi rules, so treat it as a converter rather than a registry
validator. It does flag the things that bite: labels over the 63-byte DNS limit, names
over 253 bytes, zero-width and bidi-control characters, and labels that mix Latin with
Cyrillic or Greek, the classic homograph trick behind lookalike phishing domains.
Everything runs in JavaScript on your device, so the hostnames you paste are never
uploaded.
Frequently asked questions
What is Punycode and why do some domains start with xn--?
DNS only accepts letters, digits and hyphens, so an internationalised domain name is encoded with the Punycode bootstring algorithm defined in RFC 3492 and given the ASCII Compatible Encoding prefix xn--. That is why munchen with an umlaut is stored and resolved as xn--mnchen-3ya. Browsers show you the readable form and send the xn-- form on the wire.
Does it handle full URLs and email addresses?
Yes. Paste a whole URL or address and only the host is converted, so https://bucher.example.com/preise?q=1 keeps its scheme, port, path and query, and an email keeps its mailbox name. Put one entry per line to convert a whole list at once, and use Auto-detect to encode and decode in the same paste.
Why does it warn about mixed scripts?
A label that mixes Latin with Cyrillic or Greek letters is the classic homograph trick: a Cyrillic a looks identical to a Latin a, so a lookalike domain can pass for the real one. The tool flags those labels, plus invisible zero-width and bidi characters, and any label over the 63-byte DNS limit. Conversion runs entirely in your browser, so nothing you paste is uploaded.