> ## 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.

# Run studies in multiple languages

> Reach participants in their own language across outreach and the interview.

Pillow serves your outreach in the participant's language, and your Researcher Agent runs the whole interview in that language too. Add translations for your outreach, and each participant sees the message that matches their locale.

<Info>
  Localization goes beyond outreach: the agent conducts the entire interview in the participant's language, and the chat interface is shown in that language too.
</Info>

## Supported languages

Pillow supports 25 languages:

| Language              | Locale code |
| --------------------- | ----------- |
| English (US)          | `en-US`     |
| English (UK)          | `en-GB`     |
| French                | `fr-FR`     |
| Spanish (Spain)       | `es-ES`     |
| Spanish (Argentina)   | `es-AR`     |
| Spanish (Mexico)      | `es-MX`     |
| German                | `de-DE`     |
| Italian               | `it-IT`     |
| Portuguese (Brazil)   | `pt-BR`     |
| Portuguese (Portugal) | `pt-PT`     |
| Dutch                 | `nl-NL`     |
| Polish                | `pl-PL`     |
| Russian               | `ru-RU`     |
| Japanese              | `ja-JP`     |
| Korean                | `ko-KR`     |
| Chinese (Simplified)  | `zh-CN`     |
| Chinese (Traditional) | `zh-TW`     |
| Arabic                | `ar-SA`     |
| Hindi                 | `hi-IN`     |
| Turkish               | `tr-TR`     |
| Swedish               | `sv-SE`     |
| Danish                | `da-DK`     |
| Norwegian             | `no-NO`     |
| Finnish               | `fi-FI`     |
| Vietnamese            | `vi-VN`     |

## Add languages

<Steps>
  <Step title="Write your primary outreach">
    Your first outreach message is drafted for you. Review and adjust it.
  </Step>

  <Step title="Add the languages you need">
    Click **Add language** and pick a locale, or click **Add all languages** to cover every supported language at once. Each message is translated for you, and you can edit any of them.
  </Step>
</Steps>

Translations carry the meaning and tone of your primary message, so edit them the same way you'd edit the original.

## How locale matching works

A participant's locale is detected from their browser. Pillow then picks the outreach language in this order:

1. **Exact match**: their locale matches one you've added (for example, `fr-FR`).
2. **Same language**: a variant in the same language (their `fr-CA` uses your `fr-FR`).
3. **Your default**: the study's default language.
4. **English**: `en-US` as the final fallback.

## Viewing interview language

Each interview records the participant's locale in its metadata, so you can segment your results by language. If an interview comes in a language you don't read, translate the transcript while reviewing it. See [Review interviews](/guides/review-interviews).

## What's next

<CardGroup cols={2}>
  <Card title="Create a study" icon="plus" href="/guides/create-study">
    Set up multi-language outreach from the start.
  </Card>

  <Card title="Customize outreach" icon="pencil" href="/guides/customize-outreach">
    Write the first message participants see.
  </Card>
</CardGroup>