# Introduction to Claude Code

Claude Code is Anthropic's official CLI (Command Line Interface) agentic coding assistant. Since its general availability in May 2025, it has become a critical tool for world's leading enterprises, including Netflix, Spotify, KPMG, L'Oreal, and Salesforce. In just 6 months, Claude Code reached the milestone of $1 billion in annual run-rate revenue.

## What is Claude Code?

Claude Code is not a traditional code completion tool—it's a **true Agentic Coding Assistant**. It works like an experienced developer, autonomously understanding, planning, and executing complex programming tasks.

### Core Capabilities

- **Autonomous Planning**: Understands complex tasks and creates execution plans without step-by-step guidance

- **Code Operations**: Directly reads, edits, and creates any files in your project

- **Terminal Execution**: Runs tests, installs dependencies, executes builds, and more

- **Deep Context Understanding**: 200K token context window, expandable to 1M tokens for comprehensive codebase awareness

- **Subagent Collaboration**: Spawns specialized subagents to handle specific tasks efficiently

### Major 2025 Updates

- **Plan Mode**: Analyze and research first, then create implementation plans to reduce errors

- **Subagents**: Background agents for code review, testing, and specialized tasks

- **CLAUDE.md Memory System**: Project-level config files that remember your preferences and standards

- **MCP Extension Protocol**: Connect external tools and services via Model Context Protocol

- **Opus 4.8 / 4.7 Model**: The latest and most powerful coding model (4.8 is current flagship), significantly improved code generation

## Comparison with Competitors

### Claude Code vs OpenAI Codex CLI

| Feature | Claude Code | Codex CLI |
|---------|-------------|-----------|
| Base Model | Claude Opus 5 / Sonnet 5 (4.x still on sale) | GPT-5.5 / GPT-5.4 / GPT-5.3-Codex |
| Subagent System | Native support, powerful | Requires MCP extension |
| Plan Mode | Built-in | No native support |
| Interaction Style | Detailed explanations, pair-programming | Concise output, more automated |
| Intent Understanding | Excellent, rarely misinterprets | Good, occasionally ignores instructions |
| Context Window | 200K-1M tokens | 400K tokens |
| Pricing | Pay-per-use / Subscription | Pay-per-use / Subscription |

**Verdict**: Claude Code excels in code quality, interaction experience, and intent understanding; with the 1M context option, it also matches Codex on context window size.

> **QCode.cc also supports Codex!** After purchasing a plan, Claude Code and Codex share the same quota, giving you flexibility to choose which tool to use. See [Codex Integration](/docs/ide/codex) to learn how to configure it.

### Claude Code vs Google Gemini CLI

| Feature | Claude Code | Gemini CLI |
|---------|-------------|------------|
| Pricing | Pay-per-use / Subscription | Free (with limits) |
| Context Window | 200K-1M tokens | 1M tokens |
| Coding Ability | Industry-leading | Noticeably weaker |
| Agent Features | Mature and comprehensive | Basic functionality |
| Multimodal | Image understanding | Native multimodal |
| Ecosystem | Independent | Deep Google ecosystem integration |

**Verdict**: Gemini CLI’s Pro/free/individual tiers stopped on 2026-06-18; the successor is Antigravity CLI. On capability, Gemini CLI has a huge context window but is weaker at coding than Claude Code — still not the pick for professional development. Enterprise paid keys can keep using Gemini CLI.

> **Note**: Gemini CLI stopped serving Pro/free/individual accounts on 2026-06-18 ([Google announcement](https://developers.googleblog.com/an-important-update-transitioning-gemini-cli-to-antigravity-cli/)); the successor is Google Antigravity CLI. Enterprise paid keys are unaffected. Access to Gemini models through QCode.cc is unchanged.

### Why Claude Code is the Best Choice

> "AI tool model performance is simply better when accessed directly through Codex and Claude Code, resulting in faster and more accurate results."
> — 2025 Developer Tools Review

1. **Highest Code Quality**: Claude models consistently lead in programming benchmarks

2. **Best Developer Experience**: Detailed explanations, clear planning, precise intent understanding

3. **Enterprise Validated**: The tool of choice for Netflix, Spotify, and other top enterprises

4. **Rapid Iteration**: 176 updates shipped in 2025, continuously evolving

## Why Choose QCode.cc?

Claude Code is powerful, but official pricing is steep:

- Anthropic Max Subscription: **$200/month**

- API Pay-per-use: Opus 4.8 / 4.7 **$5/$25 per million tokens** (input/output, same price)

### QCode.cc Advantages

Through QCode.cc, you get the same Claude Code functionality at **1/7 the official price**:

| Comparison | Anthropic Official | QCode.cc |
|------------|-------------------|----------|
| Monthly Plans | $200/month | $5-50/month |
| API Price | $5/$25 per M tokens | ~$0.7/$3.5 per M tokens |
| Features | Complete | Complete |
| Region Restrictions | Overseas credit card required | WeChat/Alipay supported |
| Network Speed | High latency from Asia | Asia-Pacific optimized, low latency |
| Support | English only | 7×24 multilingual support |

### Service Guarantees

- **99.9% Availability**: Enterprise-grade stability

- **Asia-Pacific Optimized**: Hong Kong/Japan nodes for low latency

- **Seamless Migration**: API compatible, just change environment variables

- **Account Protection**: Immediate issue resolution, uninterrupted service

## Quick Start

### Install Claude Code

```bash
npm install -g @anthropic-ai/claude-code

# Or install via Homebrew (macOS)
brew install --cask claude-code
```

### Configure QCode.cc

```bash
export ANTHROPIC_BASE_URL="https://api.qcode.cc/api"
export ANTHROPIC_AUTH_TOKEN="your-api-key"
```

### Start Using

```bash
cd your-project
claude
```

Then you can communicate with Claude Code in natural language:

```
> Analyze this project's architecture and find areas for optimization
> Write comprehensive unit tests for the UserService
> Refactor src/utils.js to improve code readability
```

## System Requirements

- **OS**: Windows 10+, macOS 10.15+, Linux

- **Node.js**: 18.0 or above (22 LTS recommended)

- **Network**: Stable internet connection

## Next Steps

Ready to experience the most powerful AI coding assistant?

1. Check out the [Installation Guide](/docs/getting-started/installation) to complete setup

2. Read [Quick Start](/docs/getting-started/quick-start) to learn basic usage

3. Explore [Usage Tips](/docs/usage/cli-tips) to boost your productivity