Unicode to Punycode Converter
Convert internationalized domain names to their Punycode xn-- form and back. The tool applies the RFC 3492 algorithm to each label that contains non-ASCII characters, leaves ASCII labels unchanged and processes one domain or email address per line. It helps developers, DNS administrators and marketers check how names like münchen.de or 例え.jp appear in DNS, certificates, URLs and spam filters.
Frequently asked questions
What is Punycode?
Punycode, defined in RFC 3492, represents Unicode text using only the letters, digits and hyphen allowed in domain names. Internationalized domain names store each non-ASCII label as xn-- followed by its Punycode form. Browsers show the Unicode form to users.
Can I see an example?
mañana.com becomes xn--maana-pta.com and münchen.de becomes xn--mnchen-3ya.de. The RFC 3492 sample 他们为什么不说中文 becomes xn--ihqwcrb4cv8a8dqg056pqjye. Converting back returns the original names.
Can I convert several domains at once?
Yes. Enter one domain per line and each line is converted on its own. Leading and trailing spaces are removed and empty lines stay empty.
Does the tool handle email addresses?
Yes. Only the part after the @ is converted, so the local part stays as it is. Note that a non-ASCII local part also needs SMTPUTF8 support from the mail servers.
Does it lowercase or normalize the input?
No. The tool applies Punycode exactly as RFC 3492 defines it and keeps letter case. Browsers additionally apply the UTS 46 mapping, which lowercases and normalizes, so enter domains in lowercase for results that match DNS.
Why is my Punycode rejected?
Decoding fails when an xn-- label does not hold a valid Punycode string or when the input contains non-ASCII characters on the Punycode side. Check that the label was copied completely.
Are ASCII domains changed?
No. Labels that contain only ASCII characters, such as example or com, are left exactly as they are in both directions.
Why do attackers use Punycode?
Look-alike characters from other scripts can imitate familiar brands, which is known as a homograph attack. Converting a suspicious link to Punycode reveals the real xn-- name behind it.
Is Punycode the same as URL percent-encoding?
No. Punycode only applies to the host name. Paths and query strings with non-ASCII characters are percent-encoded instead, which the URL Encoder on this site handles.
How much text can I convert?
Up to 5 MiB of text per request, one domain per line. The conversion runs on the server and nothing is stored.