Punycode Converter - IDN Encoder & Decoder
Encode Unicode domain names to Punycode for DNS registration or decode Punycode back to readable Internationalized Domain Names. Essential for working with non-ASCII top-level domains.
About Punycode
Punycode is an encoding syntax used to convert Unicode (international) domain names to ASCII format that the DNS system can understand. Internationalized Domain Names (IDNs) like .中国 or .рф are encoded with the "xn--" prefix. This allows domain names in non-ASCII scripts to work with the existing DNS infrastructure.
How it works
This tool encodes Unicode domain names to punycode (ASCII-compatible encoding) and decodes punycode back to Unicode. DNS only understands ASCII, so international domain names need conversion.
Punycode uses the "xn--" prefix followed by encoded characters. The algorithm preserves ASCII characters and encodes non-ASCII using a compact representation based on their Unicode code points.
Example conversions:
münchen.deencodes to xn--mnchen-3ya.de日本.jpencodes to xn--wgv71a.jpEnter a Unicode domain to encode, or punycode to decode. The tool validates the format and shows both representations for use in DNS configuration, SSL certificates, or email systems.
When you'd actually use this
Configuring DNS for international domains
A business registers an IDN like café.com. Their DNS provider requires the punycode version xn--caf-dma.com for zone file entries. They convert to configure DNS correctly.
Setting up SSL certificates for IDNs
Someone orders an SSL certificate for their international domain. The certificate authority needs the punycode version in the CSR, but the certificate displays the Unicode version to visitors.
Analyzing phishing attempts
A security analyst investigates a suspicious domain that looks like a legitimate site. They decode the punycode to reveal homograph attacks using lookalike Cyrillic or Greek characters.
Processing email bounces for IDN domains
A mail server admin troubleshoots bounce messages with punycode domains. They decode to readable Unicode to understand which actual domain the email was sent to.
Building domain validation tools
A developer creates a form accepting international domains. They convert to punycode for backend validation and WHOIS lookups since those systems only handle ASCII domains.
Migrating email systems with IDN
An IT admin migrates email for a company with an IDN domain. They convert between Unicode and punycode to configure MX records while keeping user-facing addresses in Unicode.
What to know before using it
Only the domain label gets encoded.Each label (between dots) converts separately. "www.münchen.de" becomes "www.xn--mnchen-3ya.de". Only labels with non-ASCII characters get the xn-- prefix.
Browsers handle conversion automatically.Modern browsers convert IDNs to punycode for DNS lookups automatically. You usually only need punycode for configuration files and APIs.
Some registries restrict IDN registration.Not all TLDs support internationalized domains. Country-code TLDs often have rules about which characters are allowed based on the language.
Email addresses need special handling.The domain part converts to punycode, but the local part (before @) may need separate encoding using SMTPUTF8 extension for full internationalization.
Security warning: Punycode enables homograph attacks where attackers register domains looking identical to legitimate ones using different Unicode characters. Always verify domains carefully, especially in emails.
Common questions
What does xn-- stand for?
xn-- is the ACE (ASCII-Compatible Encoding) prefix that identifies a punycode-encoded label. It tells DNS and browsers that the label contains encoded Unicode characters.
Can I use punycode in email addresses?
The domain part automatically converts. user@münchen.de becomes [email protected] in mail headers. Modern email clients handle this transparently.
Do search engines treat punycode domains differently?
No, search engines understand both forms are identical. They index the Unicode version for display but recognize punycode as the same domain. No SEO difference.
How do I type international domain characters?
Use your keyboard's input method for the language. On Windows, add the keyboard layout. On mobile, switch keyboards. Or copy-paste characters from a character map.
Are IDN domains more expensive?
Usually the same price as regular domains. Some registries charge slightly more for IDNs, but most price them identically to ASCII domains.
Can I convert just part of a domain?
Each label converts independently. Only labels with non-ASCII characters get encoded. ASCII labels stay unchanged in the punycode version.
Why would I use an international domain?
IDNs make domains accessible in native scripts. Local customers find them easier to remember and type in their own language. They're especially valuable for non-English markets.
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