# Localize

This topic describes how to configure the Rebilly Instruments JS library to use different languages.

## Set the default language

Use the `locale` property, in the `RebillyInstruments.mount()` function, to configure your default language. If this option is not passed, the language will default to the user's browser language.

Supported languages

- English
- Spanish



```JavaScript
import RebillyInstruments from '@rebilly/instruments';

RebillyInstruments.mount({
  publishableKey: 'pk_sandbox_123',
  organizationId: 'org-123',
  websiteId: 'my-website-id',
  apiMode: 'sandbox',
  locale: 'auto',
});
```

## Change text content

Change text content to a specific language by including it in the `i18n` property, of the `RebillyInstruments.mount()` function. This overrides the existing text with the language that is passed.

For a complete list of mount parameters, see [RebillyInstruments.mount()](/docs/dev-docs/reference-rebilly-instruments#rebillyinstrumentsmount).


```JavaScript
import RebillyInstruments from '@rebilly/instruments';

RebillyInstruments.mount({
  publishableKey: 'pk_sandbox_123',
  organizationId: 'org-123',
  websiteId: 'my-website-id',
  apiMode: 'sandbox',
  i18n: {
    en: {
      summary: {
        total: 'Your grand total'
      },
      form: {
        address: {
          cardHolderNameLabel: 'My awesome label',
        },
      }
    }
  }
});
```

## Add a new language

Add a new language by including it in the `i18n` property, of the `RebillyInstruments.mount()` function. Use a valid country ISO code to set the language ("en-ca" or "en").


```JavaScript
import RebillyInstruments from '@rebilly/instruments';

RebillyInstruments.mount({
  publishableKey: 'pk_sandbox_123',
  organizationId: 'org-123',
  websiteId: 'my-website-id',
  apiMode: 'sandbox',
  i18n: {
    'en-ca': {
      summary: {
        total: 'Thank you, your Total is:'
      }
    }
  }
});
```