Set Claude's Response Language with the language Setting

If you work in a language other than English, the language setting in settings.json tells Claude to respond in that language by default across all your sessions.

// ~/.claude/settings.json
{
  "language": "japanese"
}

Supported values are plain language names: "japanese", "spanish", "french", "german", "portuguese", "korean", "chinese", and so on. Claude treats this as a strong preference, so you can still ask questions in English and Claude will reply in the configured language.

The setting also affects push-to-talk voice dictation. When language is set and you enable /voice, the dictation engine is configured to expect that language, which improves transcription accuracy for non-English speech.

You can set this globally in user settings for a personal preference, or in project settings if the codebase documentation is written in a specific language and you want Claude to match it consistently:

// .claude/settings.json (for a French-language project)
{
  "language": "french"
}

There is no need to remind Claude of your language preference at the start of every session. Set it once and it applies everywhere.

One line removes the overhead of translating Claude's responses yourself.

via Claude Code Settings