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Punycode Converter

Convert internationalised domain names to punycode and back.

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Quick Tool Overview

The Punycode Converter encodes internationalised domain names to their xn-- form and decodes them back, label by label, so you can see exactly which parts were encoded and what an xn-- domain really says.

What it does
Converts domains between Unicode and punycode
You give it
A domain in either form
You get back
The converted domain and a per-label breakdown
Best for
IDN setup, certificate work and spotting lookalike domains
Developer Tools Free, unlimited use No sign-up Runs in your browser

About the Punycode Converter

DNS only carries ASCII, so a domain containing accents, Cyrillic, Arabic or Chinese has to be encoded before it can be resolved. Punycode is that encoding: münchen.de becomes xn--mnchen-3ya.de, and every browser does the conversion silently before it makes a request.

Each label — each dot-separated part — is encoded on its own, and only the labels that need it get the xn-- prefix, which is why a mixed domain keeps its ASCII parts unchanged. Decoding matters for a different reason: an xn-- domain in a log, an email header or a certificate is unreadable until you convert it back, and homograph attacks rely on that. Seeing the real Unicode is how you spot a Cyrillic "а" pretending to be a Latin one.

Key features of the Punycode Converter

Per-label conversion

Each dot-separated label is handled on its own, so ASCII parts such as "com" are left untouched exactly as a resolver does it.

Homograph inspection

Decoding an xn-- domain shows the real characters, which is how you catch a Cyrillic letter impersonating a Latin one.

A real RFC 3492 implementation

The full encoder and decoder, not a lookup table, so any script converts correctly in both directions.

Label breakdown

Every label is listed with its original and converted form, so a long domain is easy to check piece by piece.

Round-trip verified

The result is decoded back and compared, so you know the conversion was lossless.

How to use the Punycode Converter

  1. 1

    Pick a direction

    Unicode to punycode, or punycode back to Unicode.

  2. 2

    Paste the domain

    A full domain with dots; each label is converted separately.

  3. 3

    Read the breakdown

    Every label is listed so you can see which ones were encoded and which were left alone.

  4. 4

    Copy the result

    Take the converted domain to your clipboard.

Frequently asked questions

It is the ACE prefix, which marks a label as punycode-encoded. Without it a resolver could not tell an encoded label from a domain that happens to look like one.

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