BCP 47 Validator

This service lets you validate language tags such as de-CH or en-US according to BCP 47 (formerly RFC 4646) and the IANA Language Subtag Registry. The Language Tag Extensions Registry is not used by this service, but this may change in the future.

Separate multiple tags by comma or whitespace. Do not include quality values such as ;q=0.8. As you type, the background color denotes whether all tags are well-formed and valid, any tag is invalid or any tag is not well-formed.

Language tags:	en-UK
Output format:

Input: en-UK
Canonical: en-UK
Input is canonical: True
Well-formed: True
Valid: False
Registry date: 2025-03-10
Primary language subtag: en – English
Extended language subtags: –
Script subtag: –
Region subtag: UK – Unknown subtag of type 'region'
Variant subtags: –
Extension subtags: –
Private subtags: –
Messages: 'UK' is not a valid subtag of type 'region'.

Feedback

Don't hesitate to send suggestions and comments to Christoph Schneegans (christoph@schneegans.de).