Why this tool is useful
Use this converter to inspect DNS-safe spellings, compare multilingual hostnames and prepare deterministic test fixtures without making a DNS or HTTP request.
Developer & Data · runs locally
IDN Punycode Domain Converter
Convert internationalized domain labels between readable Unicode and canonical ASCII Punycode without resolving, visiting or submitting the domain.
Ready. Your working data stays in this browser.
How it works
Each dot-separated label is validated locally; Unicode input uses the browser's strict domain-to-ASCII path, ordinary ASCII is canonicalized to lowercase and xn-- labels are decoded only when their canonical round trip matches.
Practical example
Encoding münich.example returns xn--mnich-kva.example, while decode mode restores the Unicode label after canonical validation.
Validation
The calculation is deterministic and explains validation errors instead of silently changing invalid input.
Privacy boundary
Input and output remain in this tab. Copy and download happen through browser APIs without a server upload.
Result passport
Every run reports its tool mode, timestamp and input/output size so transformed data can be audited.