xn--mnchen-3ya.de
About Punycode Converter – IDN to xn-- (ASCII)
Punycode is the encoding behind internationalized domain names (IDNs). Because DNS only accepts ASCII letters, digits, and hyphens, a domain like `münchen.de` has to be represented on the wire as an ASCII-Compatible Encoding (ACE) string: `xn--mnchen-3ya.de`. RFC 3492 defines exactly how each non-ASCII label is transformed into that `xn--` form.
This Punycode converter translates domains in both directions, label-by-label. Paste a Unicode domain to see its `xn--` ACE form for DNS records, TLS certificates, or email routing — or paste an `xn--` domain to reveal the human-readable name behind it. ASCII-only labels are left untouched, so only the parts that need encoding change.
Everything runs locally in your browser. No domain you paste is ever uploaded, which makes this safe for inspecting internal hostnames and certificate subjects.
Features
- Convert Unicode domains to Punycode (xn-- ACE) form and back
- Per-label processing — only non-ASCII labels get the xn-- prefix
- Hand-rolled RFC 3492 algorithm, no external dependencies
- Clear errors on malformed input; works completely offline
How to use
- Paste a domain — a Unicode IDN or an xn-- ACE name — into the input pane.
- Choose "To ASCII" to encode Unicode → Punycode, or "To Unicode" for the reverse.
- Read the converted domain in the output pane and copy it with one click.
Frequently asked questions
What does the "xn--" prefix mean?
The "xn--" prefix is the ACE (ASCII-Compatible Encoding) marker defined by RFC 3492. It tells DNS resolvers and browsers that the rest of the label is a Punycode-encoded Unicode string, so "xn--mnchen-3ya" should be displayed as "münchen".
Why are only some labels of my domain changed?
Each dot-separated label is encoded independently. Labels that contain only ASCII characters are already valid for DNS and pass through unchanged, so only labels with non-ASCII characters receive the xn-- prefix. For example, "shop.münchen.de" becomes "shop.xn--mnchen-3ya.de".
Is Punycode a security risk?
Punycode itself is just an encoding, but it enables homograph attacks — domains using look-alike Unicode characters (e.g. Cyrillic "а" instead of Latin "a") that render identically to a trusted name. Browsers mitigate this by showing the raw xn-- form for suspicious mixed-script domains. Use this tool to reveal what a domain actually decodes to.
Does this handle the full IDNA spec?
This converter implements the RFC 3492 Punycode algorithm with per-label encoding and decoding, which covers the vast majority of debugging needs. It does not apply the full IDNA2008 mapping/normalization (e.g. case folding or NFC normalization) — paste domains in the exact form you want converted.
Related tools
Everything runs locally in your browser — your input is never uploaded.