🌐 Punycode / IDN Converter
Professional Punycode/IDN converter that transforms Unicode domain names to ASCII-compatible encoding (ACE) and back. Features multi-label domain parsing, ACE length validation, security warnings, and educational insights for international domain management.
Conversion Results:
café.example.com ↔ xn--caf-dma.example.com
Unicode to ASCII Compatible Encoding (ACE)
🔄 Domain Transformation
🏷️ Domain Label Analysis
✅ ACE Validation:
All labels are within the 63-character ASCII Compatible Encoding limit
⚙️ Technical Details
🔒 Security Notice
IDN Homograph Protection: Always verify domain authenticity when using international characters that may look similar to ASCII characters.
Best Practice: Use this tool to verify the Punycode representation of IDN domains before registration or DNS configuration.
How to Use This Punycode / IDN Converter
How to Use the Punycode / IDN Converter:
- Enter your domain name in the text area (Unicode or Punycode format)
- Select conversion mode or let the tool auto-detect the input type
- Enable technical details to see RFC 3492 algorithm breakdown and ACE validation
- Click "Convert Domain" to process single or multi-label domains
- Review the conversion results with per-label ACE length analysis
- Copy individual results or download the complete conversion report
Pro Tips: Use auto-detect mode for mixed input types. The tool handles complex multi-label domains like subdomains automatically. Always verify ACE length limits (63 characters per label) for DNS compatibility.
How It Works
RFC 3492 Punycode Conversion Technology:
Our converter implements the official Punycode algorithm for internationalized domain names:
- Input Detection: Automatically identifies Unicode IDN vs ASCII-compatible Punycode format
- Multi-label Parsing: Splits domains by dots and processes each label independently
- Unicode Normalization: Ensures consistent character representation before conversion
- Punycode Algorithm: Applies RFC 3492 encoding/decoding with bias adaptation
- ACE Prefixing: Adds "xn--" prefix to Punycode labels for DNS compatibility
- Length Validation: Verifies each label stays within 63-character ASCII limit
- Security Analysis: Detects potential homograph attacks and similar character confusion
- Reassembly: Reconstructs complete domain with converted labels
Technical Standards: Fully compliant with RFC 3492 (Punycode), RFC 5891 (IDNA), and UTS #46 for maximum compatibility with DNS servers and web browsers worldwide.
When You Might Need This
- • Convert international business domains like café.com to xn--caf-dma.com for DNS registration
- • Validate Punycode domains received in emails to detect potential phishing attempts using similar-looking characters
- • Transform Unicode domain names to ASCII-compatible encoding for legacy system compatibility
- • Analyze multi-label international domains like shop.münchen.de for proper subdomain configuration
- • Convert Chinese, Arabic, or Cyrillic domain names to Punycode for international SEO and accessibility
- • Decode mysterious xn-- domains in server logs back to readable Unicode for security analysis
- • Process internationalized email addresses containing non-ASCII characters in domain parts
- • Validate ACE length limits (63 chars per label) when registering long international domain names
- • Convert domains for development testing across different internationalization frameworks
- • Transform brand names with special characters into DNS-compatible ASCII encoding for trademark protection
Frequently Asked Questions
What is Punycode and why do I need to convert domains?
Punycode is an ASCII-compatible encoding method that allows Unicode characters in domain names. Since DNS servers only understand ASCII characters, international domain names (IDN) with characters like é, ü, 中, or Arabic script must be converted to Punycode format (prefixed with xn--) for proper resolution. This enables global users to register and use domains in their native languages while maintaining DNS compatibility.
How do multi-label domains work with Punycode conversion?
Multi-label domains (like subdomains) are processed label by label, separated by dots. For example, 'café.münchen.com' becomes 'xn--caf-dma.xn--mnchen-3ya.com' where each non-ASCII label gets converted independently. This allows complex internationalized domains with multiple Unicode components while ensuring each part stays within the 63-character ASCII limit required by DNS standards.
What are the ACE length limits and why do they matter?
ASCII Compatible Encoding (ACE) has a strict 63-character limit per domain label as defined by DNS specifications. When Unicode text is converted to Punycode, it often becomes longer due to the encoding algorithm. Our tool validates that each converted label doesn't exceed this limit, preventing domain registration failures and ensuring DNS compatibility across all servers worldwide.
How can I detect potential security issues with international domains?
International domains can be exploited through homograph attacks, where visually similar characters from different alphabets create confusing domains (like using Cyrillic 'а' instead of Latin 'a'). Our converter helps identify these by showing the exact Punycode representation and warns when characters might be visually confusing. Always verify the Punycode output matches your intended domain to avoid phishing attempts.
Can I convert multiple domains at once or batch process domain lists?
Yes, our tool supports batch processing by entering multiple domains (one per line) in the input field. Each domain is processed independently with full multi-label support and ACE validation. This is particularly useful for domain portfolio management, security analysis of email domains, or when migrating international websites that use various Unicode domain formats.