Setting the checkout language

By default, the BTC Direct checkout page is shown in English. The locale field lets you open the checkout in the customer’s own language.

Setting the language

Pass locale as an IETF locale (language-region) when you create the checkout session:

{
  "baseCurrency": "BTC",
  "quoteCurrency": "EUR",
  "paymentMethod": "creditCard",
  "quoteCurrencyAmount": 50,
  "walletAddress": "bc1...",
  "locale": "nl-nl"
}

The returned checkoutUrl carries the locale, so the checkout opens in that language. You do not need to add the locale to the URL yourself.

Supported languages

The checkout is available in these languages:

Language	Recommended locale
Dutch (Netherlands)	nl-nl
Dutch (Belgium)	nl-be
English	en-gb
German	de-at
French	fr-fr
Spanish	es-es

The language is taken from the first part of the locale (nl, en, de, fr, es). The region is free-form: any region pairs with a supported language, so de-at and de-de both show the checkout in German. Casing does not matter — en-gb, en-GB, and EN-GB are all accepted and normalised to lowercase.

locale is optional:

• Omitted — the checkout defaults to English.
• Rejected with ER099 — the value must be a language-region pair (two letters, a hyphen, two letters) and the language must be one of the supported languages above. A missing region (en) or an unsupported language (pt-pt) is rejected. See error codes.