Punycode Converter

Punycode is an encoding system that converts Unicode characters (non-ASCII letters, symbols, emojis) into ASCII-compatible format for use in domain names, enabling Internationalized Domain Names (IDNs). Traditional DNS only supports ASCII characters (a-z, 0-9, hyphen), but billions of internet users write in non-Latin scripts: Chinese (中文), Arabic (العربية), Cyrillic (Русский), Hebrew (עברית), and many others. Punycode solves this by encoding Unicode domains into ASCII with the xn-- prefix. Examples: 中国.com (China in Chinese) converts to xn--fiqs8s.com. münchen.de (Munich in German) becomes xn--mnchen-3ya.de. ☃.net (snowman emoji) encodes to xn--n3h.net. مصر.com (Egypt in Arabic) becomes xn--wgbh1c.com. When you type an IDN in your browser, it automatically converts to Punycode before DNS lookup, but displays the Unicode version for readability. This allows people worldwide to use domains in their native languages and scripts, promoting internet accessibility and cultural representation. Punycode is critical for: global branding (companies using native scripts), local language websites, email addresses with international characters, and inclusive internet infrastructure.

The Punycode Converter provides bidirectional conversion between Unicode (human-readable) and Punycode (DNS-compatible) formats. To encode (Unicode → Punycode): Enter an internationalized domain like 日本.jp, café.fr, or münchen.de into the converter. The tool outputs the Punycode version: xn--wgv71a.jp, xn--caf-dma.fr, xn--mnchen-3ya.de. Use this Punycode format when: configuring DNS records (most DNS control panels require ASCII), setting up SSL certificates (certificate authorities need Punycode format), entering domains in older software that doesn't support Unicode, or troubleshooting DNS issues (query the Punycode version directly). To decode (Punycode → Unicode): Enter a Punycode domain like xn--80akhbyknj4f.com and the tool reveals the Unicode representation: испытание.com (Russian for 'test'). This is useful for: understanding what xn-- domains represent (important for security - identifying phishing attempts), verifying DNS configurations match intended Unicode domains, and analyzing server logs that record Punycode versions. Practical workflow: Register your international domain through a registrar supporting IDNs, use the converter to get the Punycode version, configure DNS/SSL using Punycode, and share the Unicode version in marketing materials (browsers automatically handle conversion). Always test both formats to ensure proper resolution and display.

Homograph attacks exploit visual similarity between characters from different scripts to create deceptive domain names that appear legitimate. Attackers register IDN domains that look identical to real sites using Punycode. Attack examples: аpple.com uses Cyrillic 'а' (U+0430) instead of Latin 'a' - visually identical but different characters, encoding to xn--pple-43d.com. Users think they're visiting apple.com but reach a phishing site. pаypal.com with Cyrillic 'а' becomes xn--pypal-4ve.com - virtually indistinguishable in many fonts. micr0soft.com substitutes zero for 'o' or uses similar characters from Greek, Cyrillic. Attackers combine this with: SSL certificates (getting valid HTTPS for the fake domain makes it seem legitimate), copied website designs (cloning the real site's appearance), and email phishing (sending links that display the Unicode version). Real-world impact: In 2017, researchers demonstrated xn--80ak6aa92e.com (apple.com in Cyrillic) could fool users. Banks and popular services are frequent targets. Browser protections: Modern browsers show Punycode (xn--) in the address bar when domains mix scripts from different languages (Cyrillic + Latin), helping users spot fakes. Protection strategies: Check address bar carefully - legitimate sites won't suddenly show xn-- prefixes. Verify SSL certificate details (shows the actual registered domain). Bookmark important sites instead of typing URLs. Use password managers that match exact URLs (won't auto-fill on homograph domains). Enable browser security warnings. For website owners: monitor for similar IDN registrations, educate users about this attack vector, and consider registering similar IDN variants defensively.

Punycode algorithm (RFC 3492) encodes Unicode into ASCII using a sophisticated compression system. The process: Step 1: Extract all ASCII characters from the domain (these pass through unchanged). For münchen, extract 'mnchen'. Step 2: Encode the positions and values of non-ASCII characters efficiently. The 'ü' at position 1 is encoded. Step 3: Add the xn-- prefix. Result: xn--mnchen-3ya. The suffix '3ya' represents the Unicode character 'ü' and its position. Complex example: bücher.de (German for books). ASCII characters: 'bcher'. Non-ASCII: 'ü' at position 1. Punycode: xn--bcher-kva.de. The 'kva' encodes 'ü' and position. For fully non-ASCII domains like 中国.cn: No ASCII characters exist, so the entire domain is encoded: xn--fiqs8s.cn. Encoding rules: Uses variable-length encoding to represent Unicode efficiently. Handles multiple non-ASCII characters with positional markers. Case-insensitive (Punycode is lowercase, but represents any case Unicode). Supports all Unicode characters (65,000+ possibilities). Why the algorithm matters: It keeps encoded forms relatively short (important because DNS labels limited to 63 characters). It's reversible - decoded result always matches original Unicode. It's ASCII-safe - only uses letters, digits, and hyphens (no special characters that might break DNS). Limitations: Each label (part between dots) is encoded separately. café.münchen.de becomes xn--caf-dma.xn--mnchen-3ya.de. Maximum label length after encoding still 63 characters, limiting very long Unicode strings.

IDN support varies by TLD (top-level domain) and registry policies. Widely supported TLDs: .com, .net, .org - fully support IDNs with Punycode encoding (managed by Verisign). You can register 中文.com or café.net. Country-code TLDs (ccTLDs) with strong IDN support: .de (Germany) supports German characters like ü, ö, ä. .jp (Japan) supports Japanese characters (Hiragana, Katakana, Kanji). .cn (China) supports Chinese characters. .ru (Russia) supports Cyrillic. .sa (Saudi Arabia) supports Arabic script. .eu (European Union) supports various European scripts. .in (India) supports Devanagari and other Indian scripts. Internationalized ccTLDs: Some countries have native-script TLDs: .中国 (China in Chinese, equivalent to .cn). .рф (Russia in Cyrillic). .مصر (Egypt in Arabic). .भारत (India in Devanagari). These TLDs are themselves encoded: .中国 = .xn--fiqs8s. Limited or no IDN support: Some older or restrictive TLDs don't allow IDNs due to technical limitations or policy decisions. .gov, .mil, .edu generally restrict to ASCII. Some new gTLDs may not support all scripts. Registration requirements: Some ccTLDs restrict IDN characters to relevant scripts (e.g., .de allows German/European characters but may restrict Chinese). Before registering: Check registrar documentation for supported characters, verify the TLD allows your desired script, and test the Punycode encoding to ensure it's reasonable length. Email support often lags domain support - verify if you need email addresses with international characters.

Registration strategy: Register both the IDN (Unicode) and equivalent ASCII versions if possible. For example, register both café.com and cafe.com, with one redirecting to the other, preventing confusion and typosquatting. Register defensive variants: common misspellings, different scripts that look similar, and Punycode format explicitly. Technical implementation: Configure DNS using Punycode format in zone files and control panels (many DNS providers don't support Unicode input directly). Obtain SSL certificates using the Punycode version - certificate authorities issue certs for xn--caf-dma.fr, not café.fr directly. Test email addresses thoroughly - not all mail servers handle IDN emails correctly, even though the specification (RFC 6531) supports it. User communication: Display the Unicode version in marketing, print materials, and visual branding for readability and appeal. Include ASCII alternatives for users with older systems or limited Unicode support. Educate users that the domain might appear as xn-- in some contexts (browser address bars with security warnings, DNS tools, SSL certificate details). Browser compatibility: Modern browsers (Chrome, Firefox, Safari, Edge) fully support IDN display and conversion. However, they show Punycode for mixed-script domains to prevent homograph attacks. SEO considerations: Search engines generally handle IDNs well, treating Unicode and Punycode versions as equivalent. Use Unicode in content and meta tags for better local SEO. Email implications: Test email delivery thoroughly - some spam filters flag IDN emails. Older email clients may not display Unicode addresses correctly. Consider using ASCII domain for email even if using IDN for web. Analytics: Verify that analytics platforms track IDN traffic correctly (some may log Punycode versions separately from Unicode).