How to Use Claude Sonnet 4.5 and GPT-5 for FREE: 3 Proven Methods

Want to harness the power of Claude Sonnet 4.5 or GPT-5 without spending a fortune? You’re in the right place. In this comprehensive guide, I’ll reveal three legitimate methods to access these advanced AI models completely free. These are the exact tools I use daily for coding, automation, and content creation.

Why Use Claude Sonnet 4.5 and GPT-5?

Before diving into the free methods, let’s understand why these models are worth your attention:

The challenge? Premium pricing can be prohibitive. Claude Sonnet 4.5 costs $3-15 per million tokens, while GPT-5 has similar premium pricing. That’s where these free alternatives come in.

Method 1: Droid CLI - 40 Million Free Tokens First Month

Droid CLI by Factory AI is my top recommendation for developers who want extensive free access to premium AI models. This command-line tool offers an incredible 40 million tokens first month at no cost.

What is Droid CLI?

Droid CLI is a powerful command-line interface that provides direct access to multiple AI models including Claude Sonnet 4.5, GPT-5, and Claude Opus. It’s designed specifically for developers who prefer working in the terminal or need to integrate AI into their workflows.

Key Features

How to Get Started with Droid CLI

Step 1: Sign Up and Install

# Visit the website and create an account
# https://go.bitdoze.com/droid-cli

# Install the CLI tool (instructions provided after signup)
curl -fsSL https://app.factory.ai/cli | sh

Step 2: Launch and Configure

# Start Droid CLI
droid

# The interface will prompt you to choose your model

Step 3: Select Your Model

When you launch Droid, you’ll see options to choose between:

• Claude Sonnet 4.5
• GPT-5
• Claude Opus
• Other supported models

Step 4: Enable Reasoning (Optional)

For complex tasks requiring deep thinking, you can enable reasoning mode which allows the model to think through problems step-by-step before responding.

Real-World Usage Example

Here’s how I use Droid CLI in my daily workflow:

# Launch Droid
droid

# Select Claude Sonnet 4.5
# Enable reasoning mode for complex tasks

# Example prompt
"Create a Python web scraper that extracts product prices from e-commerce sites,
handles pagination, and exports data to CSV with error handling"

The model will process your request and provide comprehensive code with explanations. Each interaction consumes tokens from your 40 million first month allowance.

Monitoring Your Usage

Best Use Cases for Droid CLI

• Backend Development: API creation, database design, server configuration
• Automation Scripts: Task automation, data processing, workflow optimization
• Code Review: Analyzing and improving existing codebases
• Learning: Exploring new programming concepts and frameworks
• Prototyping: Rapid development of proof-of-concept applications

Get 40M Free Tokens with Droid CLI

Method 2: Windsurf IDE - 25 Free Prompts Monthly

Windsurf is a powerful AI-integrated development environment that offers 25 free prompts per month with access to premium models including Claude Sonnet 4.5 and GPT-5.

What Makes Windsurf Special?

Windsurf is more than just an IDE—it’s a complete development environment with AI deeply integrated into every aspect of your workflow. Unlike traditional IDEs with AI plugins, Windsurf is built from the ground up with AI assistance as a core feature.

Key Features

Understanding the Credit System

Windsurf uses a credit-based system where different models have different costs:

Model	Credits per Prompt	Best For
Supernova	Free (unlimited)	General coding, quick questions
Claude Sonnet 4.5	1 credit	Complex coding, reasoning tasks
GPT-5	1 credit	Advanced reasoning, content creation
GPT-4o	0.5 credits	Cost-effective premium performance

With 25 free credits monthly, you can strategically use premium models for complex tasks while leveraging Supernova for routine work.

How to Get Started with Windsurf

Step 1: Download and Install

Visit Windsurf and download the IDE for your operating system (Windows, macOS, or Linux).

Step 2: Create Your Account

Sign up for a free account to access your monthly credit allowance.

Step 3: Choose Your Mode

Windsurf offers two primary interaction modes:

• Chat Mode: Ask questions, get explanations, discuss architecture
• Code Mode: Direct file editing and project-wide changes

Step 4: Select Your Model

Open the model selector and choose based on your needs:

• Use Supernova for general tasks (free, unlimited)
• Reserve Claude Sonnet 4.5 or GPT-5 for complex problems (1 credit each)

Practical Example: Building a Snake Game

Here’s a real-world example of using Windsurf:

Prompt: "Build a snake game in Python with pygame"

The AI will:
1. Plan the project structure
2. Create necessary files
3. Implement game logic
4. Add controls and scoring
5. Provide instructions for running the game

Windsurf’s Cascade feature allows the AI to plan multi-step projects and execute them systematically, creating multiple files and organizing your project structure automatically.

Monitoring Your Usage

Best Use Cases for Windsurf

• Full-Stack Development: Complete web applications with frontend and backend
• Code Refactoring: Improving existing codebases with AI assistance
• Learning New Frameworks: Exploring React, Vue, Angular, etc.
• UI/UX Development: Creating beautiful, responsive interfaces
• Documentation: Generating comprehensive project documentation

Get 25 Free Prompts with Windsurf

Method 3: AgentRouter - $200 Free API Credits

AgentRouter is a newer service that offers an impressive $200 in free API credits to test premium models including GPT-5, Claude Sonnet 4.5, and GLM-4.5.

What is AgentRouter?

AgentRouter is an API routing service that provides access to multiple AI models through a unified interface. While it’s a Chinese company and may have occasional reliability issues, the generous $200 free credit makes it worth exploring for testing and development.

Key Features

Available Models

Model	Use Case
GPT-5	Advanced reasoning, content creation
Claude Sonnet 4.5	Complex coding, long-context tasks
GLM-4.5	Agentic tasks, tool integration

How to Get Started with AgentRouter

Step 1: Sign Up

Visit AgentRouter and create an account. You’ll immediately receive $200 in free credits.

Step 2: Create an API Key

1. Navigate to the API Keys section in your dashboard
2. Click “Create New Key”
3. Set a name (e.g., “Development Key”)
4. Choose default grouping
5. Set a quota (e.g., $10 per key for safety)
6. Optionally restrict to specific models
7. Click Submit to generate your key

Step 3: Configure Your IDE

AgentRouter works with multiple development tools. Here’s how to set it up:

For Roo Code (VS Code Extension)

// Create a new profile in Roo Code settings
{
  "profile_name": "AgentRouter Free",
  "provider": "OpenAI Compatible",
  "base_url": "https://agentrouter.org/v1",
  "api_key": "your_api_key_here",
  "model": "gpt-5",
  "enable_streaming": true
}

For Kilo Code

1. Open Kilo Code settings
2. Select “Use my own key”
3. Choose “OpenAI Compatible” provider
4. Enter base URL: https://agentrouter.org/v1
5. Paste your API key
6. Select your preferred model

Important Considerations

Real-World Testing

In my testing, I found that:

• GPT-5 works most reliably with consistent responses and fewer errors
• Claude Sonnet 4.5 occasionally times out but generally performs well
• Response times vary depending on server load
• Some IDE integrations work better than others (Kilo Code seemed more stable than Roo Code in my tests)

Monitoring Your Credits

The AgentRouter dashboard provides:

• Real-time credit balance
• Usage history and statistics
• Per-request cost breakdown
• Model-specific usage patterns

Best Use Cases for AgentRouter

• API Development: Building applications that use AI models
• Batch Processing: Processing large amounts of data
• Experimentation: Testing different models and approaches
• Cost Comparison: Evaluating which model works best for your needs
• Open Source Projects: Contributing to community projects

Get $200 Free Credits with AgentRouter

Comparison: Which Free Method is Best?

Here’s a comprehensive comparison to help you choose the right option:

Feature	Droid CLI	Windsurf	AgentRouter
Free Allowance	40M tokens/month	25 prompts/month	$200 credits
Models Available	Claude 4.5, GPT-5, Opus	Claude 4.5, GPT-5, Supernova	GPT-5, Claude 4.5, GLM-4.5
Best For	CLI users, automation	IDE development	API integration
Reliability	High	High	Moderate
Learning Curve	Medium	Low	Medium
IDE Integration	Yes	Built-in	Yes (multiple)
Renewal	First Month	Monthly	One-time credits

My Recommendations

Choose Droid CLI if you:

• Prefer working in the terminal
• Need extensive token allowance
• Want reliable, consistent performance
• Focus on backend development and automation

Choose Windsurf if you:

• Want a complete IDE experience
• Prefer visual development tools
• Need both chat and code modes
• Work on full-stack projects

Choose AgentRouter if you:

• Need API access for custom applications
• Want to test multiple models extensively
• Are building integrations
• Don’t mind occasional reliability issues

Conclusion

Access to Claude Sonnet 4.5 and GPT-5 doesn’t have to break the bank. With these three free methods, you can:

✅ Get 40 million tokens monthly with Droid CLI for extensive development work ✅ Use 25 premium prompts in Windsurf’s powerful IDE environment ✅ Experiment with $200 in credits through AgentRouter’s API

Start with all three services to maximize your free access and find which works best for your workflow. Whether you’re learning to code, building side projects, or exploring AI capabilities, these tools provide everything you need to get started without spending a cent.

Get 40M Free Tokens - Droid CLI Get 25 Free Prompts - Windsurf Get $200 Credits - AgentRouter

Remember to use these resources wisely, monitor your usage, and take advantage of all three platforms to maximize your free access to the world’s most powerful AI models. Happy coding!