Is the domain I type sent to a server?

No. The Punycode encoding and decoding run entirely in your browser with a bundled implementation of the algorithm. No DNS query or network request is made.

Why do domains get encoded as xn-- strings?

DNS only carries ASCII labels, so Internationalized Domain Names are transformed with the Punycode algorithm (RFC 3492) and prefixed with xn--. Browsers perform this conversion transparently, which is why you rarely see the raw form in the address bar.

Can this help spot homograph phishing domains?

Yes. Visually similar Unicode characters (like Cyrillic а versus Latin a) produce different Punycode. Converting a suspicious link to its xn-- form shows what will actually be resolved, making look-alike domains easier to detect.

IDN / Punycode Converter

Overview

Internationalized Domain Names (IDN) let domains contain non-ASCII characters — Japanese, Cyrillic, emoji-era Unicode in general — but DNS itself only speaks ASCII. The Punycode algorithm bridges the gap by encoding each Unicode label into an ASCII string prefixed with xn--. This tool converts in both directions, live, which is useful for registering or debugging IDNs and for inspecting suspicious look-alike links.

How to use

Type a domain into the Unicode domain field to see its ASCII form appear in Punycode (ASCII).
Or paste an xn-- domain into Punycode (ASCII) to decode it back to Unicode. Both fields are editable and convert as you type.

Examples

例え.テスト → xn--r8jz45g.xn--zckzah
xn--bcher-kva.example → bücher.example
日本語.jp → xn--wgv71a119e.jp

Notes

Conversion is applied per label (each dot-separated part); ASCII labels pass through unchanged. Malformed Punycode shows a “Could not decode Punycode” error. This tool converts notation only — it does not validate that the domain is registered or that the TLD permits the characters used.