Encode a domain name as Punycode

Convert an internationalized domain label to its ASCII Punycode form.

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ToolPunycode Encode
Input
Output
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How it works

Non-ASCII Unicode labels are transformed with Punycode’s bootstring algorithm into ASCII letters, digits, and hyphens; an xn-- prefix marks an A-label for DNS use. The conversion operates per label rather than across an entire dotted hostname.

  • ASCII labels preserve DNS compatibility while retaining a reversible Unicode mapping.

Worked example

Encode Unicode Domain
Encode a domain with Unicode characters to Punycode
Input
											üöä.com
Output
												xn--4ca9ar.com

When to use this

IDN registration, URL parsing, and certificate SAN handling encode domain labels.

Edge cases

  • The dot separator must not be encoded as part of one label.
  • Mixed-script lookalikes can remain visually deceptive after encoding.
  • A trailing hyphen or invalid code point is not a valid DNS label.

References