Developer

IDN Punycode Converter

Convert internationalized domain names (IDN) to punycode and decode xn-- punycode back to readable Unicode — instantly, in both directions, with a label-by-label breakdown.

Published September 5, 2024
Last reviewed June 27, 2026

Tool Summary Answer Block

This tool accepts structured input and returns deterministic output in the browser with no server upload.

Tool name: IDN Punycode Converter
Input intent: Provide source content to transform, validate, or analyze.
Output intent: Receive normalized output suitable for copy, reuse, or debugging.
Example input: café.com
Example output: xn--caf-dma.com

xn--

IDN · Punycode

Convert domains both ways, instantly

Paste a Unicode domain or an xn-- hostname — see both forms and a label-by-label breakdown.

Runs entirely in your browser — domains are never sent to a server.

Domain or URL

DomainDrop file

Try:

Enter a domain above to see its Unicode and punycode forms side by side.

Tool Introduction

Convert internationalized domain names (IDN) to punycode and decode xn-- punycode back to readable Unicode — instantly, in both directions, with a label-by-label breakdown.

Tool Overview

DNS and many low-level protocols only understand ASCII hostnames, so a Unicode domain like café.com is transmitted as the punycode label xn--caf-dma.com. This converter moves between the two representations using a full RFC 3492 punycode implementation that runs entirely in your browser — unlike tools that lean on the URL API, it can genuinely decode xn-- labels back to Unicode, not just re-encode them. Paste a domain, subdomain, email host, or full URL and you immediately see both the readable Unicode form and the ASCII-compatible (ACE) form, plus a per-label table showing exactly which labels are internationalized. It is built for DNS configuration, TLS certificate setup, email and link validation, backend normalization, and spotting homograph (look-alike) domains used in phishing.

Use Cases

Add an internationalized domain to DNS or a TLS certificate, which require the xn-- ASCII form
Decode an xn-- hostname from logs, headers, or a certificate back into readable Unicode
Validate and normalize email or website domains in a backend before storing them
Inspect a suspicious link for homograph attacks by comparing its punycode form
Document multilingual domains for marketing while keeping the technical ACE form handy
Debug why a Unicode URL resolves differently across browsers and email clients

Input/Output Examples

A single accented label is encoded; the .com label stays untouched.

Input Intent

café.com

Output Intent

xn--caf-dma.com

Punycode decodes back to readable Unicode.

Input Intent

xn--mnchen-3ya.de

Output Intent

münchen.de

Scheme and path are stripped, and each non-ASCII label is encoded independently.

Input Intent

https://日本語.jp/path

Output Intent

xn--wgv71a119e.jp

FAQ

What is punycode used for?+

Punycode is an ASCII encoding (RFC 3492) that represents Unicode domain labels using only the letters a–z, digits 0–9, and hyphen. Internationalized labels are prefixed with xn-- so that DNS, email, and TLS systems that only accept ASCII can still route to Unicode domains.

Can it actually decode xn-- back to Unicode?+

Yes. This tool implements the full punycode algorithm, so xn--caf-dma.com correctly decodes to café.com. Many converters that rely only on the browser URL API cannot do this and return the punycode unchanged.

Can I paste a full URL or an email address?+

Yes. The converter strips the scheme, path, and query from URLs and keeps the part after @ in an email, then converts only the hostname labels.

Does it convert every part of the domain?+

It converts each label (the parts separated by dots) independently. Labels with non-ASCII characters get the xn-- punycode form; pure-ASCII labels such as com or org are left exactly as they are.

How does this help with phishing and homograph attacks?+

Attackers register domains using look-alike characters from other scripts (for example a Cyrillic 'а' that resembles a Latin 'a'). Viewing the punycode form reveals the real, unambiguous hostname, so you can tell a spoofed domain from a legitimate one.

Is my data sent anywhere?+

No. All conversion happens locally in your browser with no network requests, which makes it safe for internal hostnames and sensitive infrastructure.