Multi-Language Chatbot: Automatic Language Detection and Response
A visitor writes in German. Your chatbot replies in English. They leave. AIWU can detect a visitor’s language automatically and respond in that same language — using one chatbot, one configuration, zero extra API keys. This guide shows you how to enable and fine-tune multilingual behavior.
Before You Start
You’ll need:
- A working chatbot (Set Up First Chatbot guide)
- Time needed: ~5 minutes
- Plan required: Free — automatic language detection is built into all major AI models
Option A: Enable Auto Language Detection (Recommended)
Go to WordPress Admin → AI Copilot → AI ChatBots. Click your chatbot → Settings tab.
Find the Language section. Set Response Language to Auto-detect (match visitor language).
Click Save Changes. Done — the chatbot will now reply in whatever language the visitor writes in.
Test it: Open the chatbot in incognito and type a message in French, Spanish, or German. The response should be in the same language.
Option B: Fix the Language Manually
If your site serves a single non-English market, set a fixed language instead of auto-detect:
In the same Language section, set Response Language to your target language (e.g. German, French, Spanish).
The chatbot will always respond in that language regardless of what language the visitor uses. Good for dedicated country stores or when you want strict brand-voice control.
Making Your Training Data Multilingual
Auto-detect handles the response language — but your training data (embeddings) may only be in one language. Here’s what happens with each search mode:
| Search Mode | Cross-language retrieval | Notes |
|---|---|---|
| Semantic (embeddings) | ✅ Yes | Semantic search finds relevant content even when the question and documents are in different languages |
| Keyword | ❌ No | Keyword search requires exact word matching — a French question won’t match English keywords |
| Hybrid | ⚠️ Partial | Semantic component works cross-language; keyword component doesn’t |
Recommendation: Use Semantic search mode if you serve multilingual visitors with a single-language knowledge base. Or add translated documents to your dataset for languages that make up 20%+ of your traffic.
Configuring the System Prompt for Multilingual Use
For the most reliable multilingual behavior, add an explicit instruction in your chatbot’s system prompt. Go to the Context tab and include:
Always respond in the same language the visitor is using. If they write in French, respond in French. If they write in Spanish, respond in Spanish. If you're unsure of the language, respond in English. Your knowledge base is in English, but you should still retrieve relevant information from it and present the answer in the visitor's language.
This explicit instruction improves consistency — especially for less common languages where auto-detect alone may be less reliable.
Advanced: Language-Specific Welcome Messages
The welcome message always displays in the language you wrote it in. For multilingual sites, either:
- Write a neutral, short welcome that works in all languages: “Hello! / Hola! / Bonjour! 👋”
- Or leave the welcome message in English and add a note: “I can assist you in any language”
- Advanced: Use WPML or Polylang with AIWU’s language conditions to show different chatbots per language version of your site
Supported Languages
GPT-4o and Claude support 50+ languages fluently. Languages with the strongest performance include English, Spanish, French, German, Portuguese, Italian, Dutch, Russian, Chinese (Simplified/Traditional), Japanese, Korean, Arabic, and Hindi. Smaller or regional languages may produce lower quality responses — test your specific languages before deploying.
Common Issues
Problem: “Chatbot auto-detects the language but still replies in English sometimes.”
Fix: Add the explicit system prompt instruction from above. Also check if you have a line in your system prompt like “You are an English-speaking assistant” — remove it.
Problem: “Non-English questions get no answers from my knowledge base.”
Fix: Switch your search mode to Semantic (embeddings-only). Semantic search works cross-language — keyword search doesn’t. See Train Chatbot with Embeddings.
Problem: “Quality in a specific language (e.g. Turkish, Czech) is poor.”
Fix: Switch to a model with stronger multilingual support — Claude 3.5 Sonnet or GPT-4o. Smaller/cheaper models have weaker multilingual performance.
What’s Next
- 🎨 Match the chatbot look to your site: Customize Chatbot Appearance
- 📊 See which languages your visitors use: Chatbot Analytics guide
- 💬 Build a full support flow: Customer Support Chatbot: Handle 80% of Tickets
Last verified: AIWU v.4.9.2 · Updated: 2026-02-25