Developer / Domains
Punycode Converter for International Domain Names (IDN)
Convert an internationalised domain name such as münchen.de to its ASCII xn-- form for DNS and back, and get a warning when a label mixes Latin with Cyrillic or Greek letters that look alike.
Punycode Converter for International Domain Names (IDN): Each label with non-ASCII characters is encoded with the Punycode algorithm of RFC 3492 and given the xn-- prefix: münchen.de becomes xn--mnchen-3ya.de and 例え.テスト becomes xn--r8jz45g.xn--zckzah. xn-- labels are decoded back. A label that mixes Latin letters with Cyrillic or Greek ones is flagged, because such names can impersonate familiar domains. Runs 100% locally in your browser with zero server file uploads.
- Category
- Developer tools
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- In your browser
- Cost
- Free · no sign-up
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- Ready to use
Runs entirely in your browser
DNS only carries letters, digits, and hyphens, so each label with other characters is written in Punycode (RFC 3492) and prefixed with xn--: münchen.de becomes xn--mnchen-3ya.de. Labels are lower-cased and normalised first; registries may apply extra rules, such as for ß or emoji, that this tool does not check. Browsers show the xn-- form when a name mixes scripts that look alike, to protect against look-alike domains.
How Punycode works
The ASCII letters of a label are copied first, followed by a hyphen; each other character is then encoded as a number giving its code point and position, written in base 36 with letters and digits. That is why bücher becomes bcher-kva: bcher, then kva for the ü.
Look-alike domains
Cyrillic а, е, о, р, and с look the same as Latin a, e, o, p, and c, so pаypal.com with a Cyrillic а is a different domain. The invisible character detector shows such characters in any text.
How to use it
- Paste a domain in Unicode or xn-- form.
- Read the ASCII and Unicode forms.
- Check the warning for mixed-script labels.
Privacy & limitations
Converted in your browser.
Related tools
Frequently asked questions
Why do I see xn-- in my browser's address bar?
Browsers show the Punycode form when a name mixes scripts or uses characters that could be confused, so a look-alike of a known site cannot pass as the real one.
Is the result the same as my registrar's?
For ordinary names, yes. Registries apply extra rules for some characters, such as German ß or emoji, which this tool does not check.
Do email addresses work?
Only the domain part after @ is converted to Punycode; the part before it is handled separately by mail servers.
Free tool · runs in your browser · no account required