Punycode Encode & Decode

What is Punycode?

Punycode is a character encoding scheme defined by RFC 3492 that allows Unicode characters to be represented using the limited ASCII character set. It's primarily used for Internationalized Domain Names (IDN), enabling domain names to contain non-ASCII characters like accents, umlauts, Chinese characters, Arabic script, and more.

Punycode converts Unicode domain names into ASCII-Compatible Encoding (ACE) format that can be safely transmitted through DNS and other systems that only support ASCII characters. The resulting encoded strings are prefixed with "xn--" to indicate they contain Punycode encoding.

How Punycode Works

Encoding: Unicode domain names are transformed into ASCII format using a specific algorithm. Non-ASCII characters are encoded while ASCII characters remain unchanged. The entire encoded string is prefixed with "xn--" to indicate Punycode encoding.

Decoding: Punycode strings (identified by the "xn--" prefix) are converted back to their original Unicode representation, restoring the international characters.

Examples

  • café.com → xn--caf-dma.com
  • bücher.de → xn--bcher-kva.de
  • 中文.com → xn--fiq228c.com
  • москва.рф → xn--80adxhks.xn--p1ai

Why is Punycode Important?

Punycode enables global internet accessibility by allowing domain names in native scripts and languages:

  • Global Accessibility: Users can register and access domains in their native languages and scripts.
  • DNS Compatibility: Maintains compatibility with existing DNS infrastructure that only supports ASCII.
  • Cultural Representation: Preserves linguistic and cultural identity in domain names.
  • SEO Benefits: Local-language domains can improve search rankings in specific regions.

Use Cases

  • Internationalized Domain Names: Registering domains with non-ASCII characters for global websites.
  • Web Development: Converting between Unicode and ASCII formats for domain processing.
  • Email Systems: Handling international email addresses with non-ASCII domain parts.
  • Browser Implementation: Converting user-entered international domains for DNS resolution.
  • SSL Certificates: Generating certificates for international domain names.
  • API Integration: Processing international domains in web services and applications.

Security Considerations

While Punycode enables international domains, it can also be misused for security attacks:

  • Homograph Attacks: Using similar-looking characters from different scripts to create deceptive domains.
  • Phishing: Creating domains that visually resemble legitimate sites using international characters.
  • Browser Protection: Modern browsers implement IDN policies to protect users from confusable characters.

How to Use This Tool

  1. Select either "Encode" mode to convert Unicode domains to Punycode, or "Decode" mode to convert Punycode back to Unicode.
  2. Enter your domain name or text in the input field. For encoding, use Unicode characters. For decoding, use Punycode format (typically starting with "xn--").
  3. The result appears automatically in the output field as you type.
  4. Use the swap button to exchange input and output, automatically switching the conversion mode.
  5. Click the copy icon to copy the result to your clipboard.
  6. Error messages will appear for invalid input formats or encoding/decoding failures.

Note: This tool processes data entirely in your browser for privacy and security. No domain information is sent to external servers.