Introduction: A Coding Agent You Can Talk To

Qwen3-Coder isn’t just an LLM that writes code — it’s a full agentic system that can:

• Use developer tools via CLI

• Build and run real-time UI in Web Dev Mode

• Simulate environments and physics

• Collaborate step-by-step like a human engineer

In this article, we’ll walk through how to use the Qwen3-Coder CLI and Web Dev Mode, and why they’re game changers for developers and researchers.

---

1. What Is Qwen3-Coder CLI?

The Qwen Agent CLI is a terminal interface that runs Qwen3-Coder in “agent mode.” It allows the model to:

• Plan multi-step coding tasks

• Read, write, and modify files

• Execute code or command-line instructions

• Use memory and tools as part of its workflow

Setup:

bash
git clone https://github.com/QwenLM/Qwen-Agent.git
cd Qwen-Agent
pip install -r requirements.txt
python cli.py --model Qwen3-Coder-480B-A35B-Instruct

Requires 2× A100 GPUs or vLLM server for smooth performance

---

2. What Can the CLI Agent Do?

Example:

Prompt:

"Create a Python app that records audio, saves as MP3, and lets me replay it."

Result:
Qwen3-Coder plans the structure, generates each module, and even debugs errors if execution fails.

---

3. What Is Web Dev Mode?

Web Dev Mode allows Qwen3-Coder to:

• Build HTML/CSS/JS UIs from natural prompts

• Simulate physics, animations, and interactive games

• Visualize logic flow and generate visual outputs

• Execute browser-like logic

Run this via tools like Cline [act mode] or local preview environments.

---

4. Use Cases for Web Dev Mode

---

5. Sample Prompt and Output (Web Dev Mode)

Prompt:

"Create an HTML + JS page that simulates a bouncing ball with gravity and air resistance."

Qwen3 Output:

• Full HTML scaffold

• Canvas setup with draw/update loop

• Physics-based velocity decay and rebound

• Click-to-reset feature

No additional libraries required

---

6. CLI vs Web Dev Mode – What’s the Difference?

---

7. Real-World Applications

• Startup MVPs – Let Qwen3 scaffold working app prototypes

• STEM educators – Simulate physical systems in-browser

• UI Designers – Convert prompts into styled layouts

• DevOps/SREs – Use CLI to automate script writing or CI/CD tasks

• AI Research – Run interactive benchmarks or algorithm visualizations

---

Conclusion: A Developer Co-Pilot You Control

Qwen3-Coder’s CLI + Web Dev Mode make it the most agentic coding model available in open-source. Unlike traditional code LLMs, it:

• Thinks across steps

• Uses tools

• Writes + executes code

• Builds live visual environments

It’s not just a coder — it’s your autonomous dev assistant.

---

Resources

• Qwen3-Coder on Hugging Face

• Run Qwen Agent CLI

• Web Dev Mode & UI Prompts

• Use Cases with Code

---