What does it do?
It converts internationalised domain names — with accents, ñ, umlauts or non-Latin scripts — into their ASCII Punycode form (xn--…) and back.
| Unicode | Punycode |
|---|
españa.com | xn--espaa-rta.com |
münchen.de | xn--mnchen-3ya.de |
例え.テスト | xn--r8jz45g.xn--zckzah |
How to use it
- Paste one domain, email address or URL per line.
- Only the host is converted: paths, query strings and the local part of emails stay as they are.
- Press Swap to decode
xn-- domains back to Unicode.
You need the Punycode form when configuring DNS records, TLS certificates, CORS allow-lists or cookies for an internationalised domain.
Frequently asked questions
›Why do domains with accents need Punycode?
DNS only understands ASCII letters, digits and hyphens. Internationalised domain names (IDN) are stored as xn-- labels, and browsers show the Unicode version to users.
›What about the part before the @ in an email?
Only the domain is converted. Non-ASCII local parts (josé@…) need SMTPUTF8 support on the mail servers and are left unchanged.
›What is an IDN homograph attack?
Registering a domain that looks identical to another using letters from other alphabets, like a Cyrillic а in аpple.com. Converting to Punycode reveals the trick: the domain becomes xn--pple-43d.com.