Punycode

Convert internationalized domains to Punycode and back

DNS stores internationalized domains as xn--. Type into either field, one domain, email address or link per line, and the other field fills in.

Unicode, what people read

Punycode, what DNS stores

Conversion runs in your browser, domains go nowhere.

Cyrillic top-level domains in Punycode

Seeing xn--p1ai in logs, email or a hosting panel? That is the Russian .рф zone. The other Cyrillic zones are below.

Zone	Punycode	Used by
.рф	xn--p1ai	Russia
.рус	xn--p1acf	Russian-language sites
.москва	xn--80adxhks	Moscow
.дети	xn--d1acj3b	sites for children
.онлайн	xn--80asehdb	any site
.сайт	xn--80aswg	any site
.орг	xn--c1avg	organizations
.ком	xn--j1aef	companies
.укр	xn--j1amh	Ukraine
.бел	xn--90ais	Belarus
.қаз	xn--80ao21a	Kazakhstan
.срб	xn--90a3ac	Serbia
.мкд	xn--d1alf	North Macedonia
.мон	xn--l1acc	Mongolia

Letters of a national alphabet pass through a prism and turn into Punycode

What Punycode is

DNS only understands Latin letters, digits and hyphens. Your browser turns münchen.de into xn--mnchen-3ya.de with the Punycode algorithm from RFC 3492 and shows the original spelling in the address bar.

Each label of the domain gets encoded on its own with an xn-- prefix. Latin labels stay the same: bücher.example.com becomes xn--bcher-kva.example.com.

Cyrillic а, е, о, р, с and х look exactly like their Latin twins. Scammers register a domain with one swapped letter and pass it off as a well-known site. The converter flags labels that mix scripts.

When it helps

Your hosting panel, DNS or nginx config only accepts xn--, and your domain has accents or non-Latin letters.
An xn-- address turned up in logs or an email, and you want to know what site it is.
You check a link from an email for swapped letters.
You prepare a domain list for an SSL certificate or a scraper.

Questions and answers

01What does xn--p1ai mean?

It is the Russian .рф zone in Punycode. Labels in front of it with the xn-- prefix are Cyrillic too: xn--e1afmkfd.xn--p1ai reads as пример.рф.

02How do I put an IDN domain into nginx or DNS?

Use Punycode in configs: server_name xn--mnchen-3ya.de; and the same name in the DNS zone. Browsers convert the address both ways by themselves.

03Can I convert an email address to Punycode?

The domain after @ converts like any other. The mailbox name before @ stays as it is: only servers with SMTPUTF8 accept non-Latin letters there.

04How do I spot a fake domain with swapped letters?

Paste the address here. A domain with a Cyrillic а instead of a Latin a starts with xn--, and the check shows which scripts it mixes.

05Why does the browser show a domain as xn-- instead of letters?

That is the browser's guard against spoofing. When a name mixes scripts or uses letters that look Latin, it shows the Punycode. A name written in one script without lookalike letters shows as is.