Building an Intelligent Chatbot with Qwen3 Instruct and Thinking Models

A step-by-step tutorial on building an interactive chatbot using Qwen3's dual-mode architecture, which supports both fast Instruct responses and deep Thinking (chain-of-thought) reasoning. Covers Qwen3's model family (dense and MoE variants from 0.6B to 235B parameters), its 3-stage training pipeline on 36 trillion tokens, and benchmark performance. The implementation uses Hugging Face Transformers pipelines for both Qwen3-4B-Instruct and Qwen3-4B-Thinking models, with a Gradio web interface that lets users switch between modes and view collapsible reasoning traces. Part 1 of a 4-part series that will later add vision, safety, and RAG capabilities.