ChatLab handles languages from a single Settings > Languages menu. From there you set the language your chatbot replies in, the language used for behind-the-scenes summaries and insights, and - when you want one bot to serve everyone - automatic Multi-language translation of the whole chat interface.
Settings > Languages: the AI language card
Select your chatbot, open the Settings tab, then click Languages in the left sidebar. The top AI language card holds two settings.
Response language
The Response language field controls which language the chatbot uses for text replies.
- Auto Detect (default) - the chatbot recognises the visitor's language and answers in that same language. Best for a mixed audience.
- Specific language (for example English, Spanish, German) - the chatbot defaults to that language and only switches if the visitor explicitly asks.
This is the setting that used to be called Primary language and lived under Settings > Role & Behavior - it is now the Response language here in Settings > Languages.
Note: when the bot uses a custom prompt (Settings > Role & Behavior > Custom Role Definition), the Response language field is disabled. In that case the language is controlled by your prompt instead - add a rule such as "Always respond in Spanish unless the visitor writes in another language".
Reporting language
The Reporting language field sets the language used for content that only you see in the admin panel:
- Conversation summaries - the AI-generated summary of each conversation
- Client summaries - the AI-generated profile of a returning visitor
- AI Insights - the periodic AI analysis of your conversations
It does not affect anything your visitors see. This is the setting that used to be called Internal language under Settings > Model & Advanced - it is now the Reporting language in Settings > Languages.
Click Save Changes after adjusting either field.
Serving a multilingual audience
The recommended way to support visitors in many languages is Multi-language, in the same Settings > Languages menu. When enabled, the chat interface, welcome messages, suggested questions and forms are translated automatically, and visitors get a language switcher in the chat window - so a single chatbot serves every language.
This replaces the old approach of translating every predefined message by hand, or running a separate chatbot per language section of your website.
For the full walkthrough - enabling Multi-language, choosing a base language, offering a fixed language list, and editing individual translations - see Multilingual chatbots.
If Multi-language is not available on your plan, you can still serve a single audience well: set one Response language (or leave it on Auto Detect) and translate your key predefined messages by hand in their own settings sections (Settings > Chat Conversation for the welcome message, suggested questions and input placeholder, plus Appearance, Lead Collection, Human Contact Form, Live Chat and Consent & Privacy where enabled).
Voice languages
Voice languages are configured separately, in Settings > Voice Conversation, and depend on the voice model:
- ElevenLabs Voice - a Language section appears with a Default language (the language the agent starts the call in) and Additional languages (extra languages it may switch into when it hears the caller speaking them).
- GPT Realtime / Gemini Voice - no language picker. These providers detect the caller's language automatically and follow your prompt. To bias them, mention the language in Settings > Role & Behavior (for example, "Always respond in Polish unless the caller speaks another language").
For the detailed voice setup, see Voice conversation.
Training a chatbot for multiple languages
You do not need to duplicate your knowledge across languages - the AI can answer in one language from content trained in another. Duplicating the same content wastes training capacity without adding new knowledge, so train with unique content and let the chatbot translate on the fly.
When scanning a website, ChatLab now detects each page's language, which helps the bot pick the right source when answering. See Adding new website sources for how website scanning works.
Frequently asked questions
Do my custom instructions need to be in a specific language?
No. Custom instructions work in any language - write them entirely in your target language, entirely in English, or mixed. What matters is that they clearly describe the behaviour you want. See Bot behavior customization for details.
Can the chatbot use training data in one language to answer in another?
Yes. The AI can use knowledge from one language to generate responses in another. Nuanced or culturally specific content may not translate as accurately, so provide training data in the languages your visitors use most.
Why is the Response language field greyed out?
Because the bot uses a custom prompt (Settings > Role & Behavior > Custom Role Definition). With a custom prompt the response language is controlled by the prompt itself, so the field is disabled - add a language rule to your prompt instead.