qwen-code/docs/users/features/language.md

Internationalization (i18n) & Language

Qwen Code is built for multilingual workflows: it supports UI localization (i18n/l10n) in the CLI, lets you choose the assistant output language, and allows custom UI language packs.

Overview

From a user point of view, Qwen Code’s “internationalization” spans multiple layers:

Capability / Setting	What it controls	Where stored
/language ui	Terminal UI text (menus, system messages, prompts)	~/.qwen/settings.json
/language output	Language the AI responds in (an output preference, not UI translation)	~/.qwen/output-language.md
Custom UI language packs	Overrides/extends built-in UI translations	~/.qwen/locales/*.js

UI Language

This is the CLI’s UI localization layer (i18n/l10n): it controls the language of menus, prompts, and system messages.

Setting the UI Language

Use the /language ui command:

/language ui zh-CN    # Chinese
/language ui en-US    # English
/language ui ru-RU    # Russian
/language ui de-DE    # German

Aliases are also supported:

/language ui zh       # Chinese
/language ui en       # English
/language ui ru       # Russian
/language ui de       # German

Auto-detection

On first startup, Qwen Code detects your system locale and sets the UI language automatically.

Detection priority:

1. QWEN_CODE_LANG environment variable
2. LANG environment variable
3. System locale via JavaScript Intl API
4. Default: English

LLM Output Language

The LLM output language controls what language the AI assistant responds in, regardless of what language you type your questions in.

How It Works

The LLM output language is controlled by a rule file at ~/.qwen/output-language.md. This file is automatically included in the LLM's context during startup, instructing it to respond in the specified language.

Auto-detection

On first startup, if no output-language.md file exists, Qwen Code automatically creates one based on your system locale. For example:

• System locale zh creates a rule for Chinese responses
• System locale en creates a rule for English responses
• System locale ru creates a rule for Russian responses
• System locale de creates a rule for German responses

Manual Setting

Use /language output <language> to change:

/language output Chinese
/language output English
/language output Japanese
/language output German

Any language name works. The LLM will be instructed to respond in that language.

Note

After changing the output language, restart Qwen Code for the change to take effect.

File Location

~/.qwen/output-language.md

Configuration

Via Settings Dialog

1. Run /settings
2. Find "Language" under General
3. Select your preferred UI language

Via Environment Variable

export QWEN_CODE_LANG=zh

This influences auto-detection on first startup (if you haven’t set a UI language and no output-language.md file exists yet).

Custom Language Packs

For UI translations, you can create custom language packs in ~/.qwen/locales/:

• Example: ~/.qwen/locales/es.js for Spanish
• Example: ~/.qwen/locales/fr.js for French

User directory takes precedence over built-in translations.

Tip

Contributions are welcome! If you’d like to improve built-in translations or add new languages. For a concrete example, see PR #1238: feat(i18n): add Russian language support.

Language Pack Format

// ~/.qwen/locales/es.js
export default {
  Hello: 'Hola',
  Settings: 'Configuracion',
  // ... more translations
};

Related Commands

• /language - Show current language settings
• /language ui [lang] - Set UI language
• /language output <language> - Set LLM output language
• /settings - Open settings dialog