> ## Documentation Index
> Fetch the complete documentation index at: https://docs.trypillow.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Supported languages

> Every language a study can run in, the language of the chat interface, and how Pillow picks a language for each participant.

This table lists every language you can add to a study under **Supported languages**, with its code and the language of the chat interface (buttons, input field, and status messages) for a participant who speaks it.

| Language                      | Code    | Chat interface        |
| ----------------------------- | ------- | --------------------- |
| English (United States)       | `en-US` | English               |
| English (United Kingdom)      | `en-GB` | English               |
| French (France)               | `fr-FR` | French                |
| Spanish (Argentina)           | `es-AR` | Spanish               |
| Spanish (Spain)               | `es-ES` | Spanish               |
| Spanish (Mexico)              | `es-MX` | Spanish               |
| German (Germany)              | `de-DE` | German                |
| Italian (Italy)               | `it-IT` | Italian               |
| Portuguese (Brazil)           | `pt-BR` | Portuguese (Brazil)   |
| Portuguese (Portugal)         | `pt-PT` | Portuguese (Portugal) |
| Dutch (Netherlands)           | `nl-NL` | Dutch                 |
| Polish (Poland)               | `pl-PL` | Polish                |
| Russian (Russia)              | `ru-RU` | Russian               |
| Japanese (Japan)              | `ja-JP` | Japanese              |
| Korean (South Korea)          | `ko-KR` | Korean                |
| Chinese (Simplified, China)   | `zh-CN` | Chinese (Simplified)  |
| Chinese (Traditional, Taiwan) | `zh-TW` | Chinese (Traditional) |
| Arabic (Saudi Arabia)         | `ar-SA` | Arabic, right to left |
| Hindi (India)                 | `hi-IN` | Hindi                 |
| Turkish (Turkey)              | `tr-TR` | Turkish               |
| Swedish (Sweden)              | `sv-SE` | Swedish               |
| Danish (Denmark)              | `da-DK` | Danish                |
| Norwegian (Norway)            | `no-NO` | Norwegian             |
| Finnish (Finland)             | `fi-FI` | Finnish               |
| Vietnamese (Vietnam)          | `vi-VN` | English               |

## How Pillow picks a participant's language

A participant's language comes from the `pillow_locale` parameter in the study link when it's there, and from their browser otherwise. Pillow matches it against the languages the study supports, in this order:

1. **Exact match:** the study supports the participant's language code (`fr-FR` for `fr-FR`).
2. **Same language:** the study supports another variant of the same language (`fr-FR` for a participant in `fr-CA`).
3. **Default language:** the study's default language.

The outreach message and the interview guide always use the same matched language. During the interview, the agent continues in the language of the participant's first reply when the study supports that language. A participant who comes back to an interview they started continues in the same language.

## Choose the language in the link

Add `pillow_locale` with a code from the table to send participants a link in a specific language, for example `?pillow_locale=es-MX` (or `&pillow_locale=es-MX` if the link already has parameters). The code goes through the same matching rules, so a code the study doesn't support gets the closest match.

## Chat interface language

The chat interface follows the participant's own language, not the study's languages: a participant whose browser is set to German sees German buttons even in a study that supports only English. The interface is translated into 21 languages; a participant in any other language, including Vietnamese, sees it in English. A browser set to Portuguese or Chinese with no region gets Portuguese (Brazil) or Chinese (Simplified).

## Related

<CardGroup cols={2}>
  <Card title="Interview in multiple languages" icon="globe" href="/guides/multi-language">
    Add languages to a study and check each one.
  </Card>

  <Card title="Participant metadata" icon="tag" href="/reference/participant-metadata">
    Other parameters you can add to the study link.
  </Card>
</CardGroup>