Free Toolkit

Punycode EncodeConvert internationalized domain names to Punycode (xn--) format.

Punycode Encode illustration
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Punycode Encode

Convert internationalized domain names to Punycode (xn--) format.

How to Use
1

Enter Domain

Type or paste the internationalized domain name.

2

View Punycode

The Punycode-encoded domain appears instantly.

3

Copy Result

Click Copy to copy the encoded domain.

What Is Punycode Encode?

Punycode represents internationalized domain names (IDN) using only ASCII characters. It converts Unicode domain labels to ASCII-compatible encoding (ACE) prefixed with xn--. Defined in RFC 3492 and used by DNS which only supports ASCII. The algorithm uses delta encoding of code points with a generalized variable-length integer representation. This tool encodes each label separately. All processing is client-side.

Why Use Our Punycode Encode?

  • Convert international domains to DNS-compatible ASCII format
  • RFC 3492 compliant Punycode encoding
  • 100% client-side — data never leaves your browser
  • Free online tool for domain name testing

Common Use Cases

Domain Registration

Check Punycode form of international domains before registration.

DNS Configuration

Get ASCII form of IDN domains for DNS records.

Email Configuration

Configure email servers with Punycode domain forms.

Security Analysis

Detect Punycode-based homograph attacks.

Technical Guide

Punycode encoding separates ASCII and non-ASCII characters. ASCII characters are copied directly followed by a dash separator. Non-ASCII code points are delta-encoded using a generalized variable-length integer with adaptive bias. The xn-- prefix identifies the label as Punycode. Each domain label between dots is encoded independently.

Tips & Best Practices

  • 1
    The xn-- prefix identifies a Punycode-encoded domain label
  • 2
    Each label between dots is encoded separately
  • 3
    Use to detect homograph attacks
  • 4
    Only needed for domain names — URLs use percent-encoding for paths

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Frequently Asked Questions

QIs this tool free?
Yes, completely free with no signup required.
QIs my data secure?
Yes. All processing is 100% client-side.
QWhat is the xn-- prefix?
xn-- is the ACE prefix that identifies a Punycode-encoded domain label.
QWhat browsers are supported?
All modern browsers including Chrome, Firefox, Safari, and Edge.
QCan I encode full URLs?
This tool encodes domain names. For URL paths, use the URL Encoder.

About Punycode Encode

Punycode Encode is a free online tool from FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration required. No ads. Just fast, reliable tools.