Punycode Converter
Convert internationalized domain names (IDN) to and from Punycode
Common Examples
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What is Punycode?
Punycode is an encoding syntax used to represent Unicode characters within the limited character set (ASCII) allowed in domain names. It enables Internationalized Domain Names (IDN) that contain non-ASCII characters like ü, ñ, 中文, or العربية to work on the internet's domain name system (DNS).
This free online Punycode converter transforms Unicode domain names to their ASCII-compatible encoding (ACE) and back. Essential for developers, domain administrators, and anyone working with internationalized web addresses.
How Punycode Works
The xn-- Prefix
Punycode-encoded labels start with "xn--" to indicate they contain encoded Unicode characters. This prefix tells DNS resolvers to decode the label.
Encoding Process
ASCII characters are preserved. Non-ASCII characters are encoded using a bootstring algorithm that efficiently represents Unicode code points using only the characters a-z, 0-9, and hyphen.
Common Use Cases
Domain Registration
Register domains with special characters. Registrars often require the Punycode version.
SSL Certificates
Configure SSL/TLS certificates for IDN domains using their Punycode representation.
DNS Configuration
Set up DNS records for internationalized domains in zone files and DNS management.
Security Analysis
Detect homograph attacks where similar-looking Unicode characters impersonate legitimate domains.
Security: IDN Homograph Attacks
Malicious actors can register domains using Unicode characters that look identical to ASCII letters. For example, Cyrillic "а" (U+0430) looks like Latin "a" (U+0061).
- apple.com vs аррle.com (Cyrillic а, р, р)
- Punycode reveals the difference: xn--pple-43d.com
- Modern browsers show Punycode for mixed-script domains
Frequently Asked Questions
Why is Punycode needed?
The DNS system was designed before Unicode existed and only supports ASCII (a-z, 0-9, hyphen). Punycode bridges this gap, allowing domain names in any language.
Will browsers show Punycode or Unicode?
Browsers display Unicode for trusted scripts (e.g., Japanese on .jp domains) but show Punycode for suspicious mixed-script domains to prevent phishing.
Is Punycode an encryption?
No, Punycode is encoding, not encryption. It's a reversible transformation for compatibility, not security. Anyone can decode xn-- domains.