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Meet the Claude 4.5 Family
Claude Sonnet 4.5
The Intelligence Powerhouse
Most capable model for complex reasoning, coding, analysis, and creative tasks. Model ID: claude-sonnet-4-5-20250929
Most capable model for complex reasoning, coding, analysis, and creative tasks. Model ID: claude-sonnet-4-5-20250929
Claude Haiku 4.5
The Speed Champion
Fastest model optimized for high-volume, low-latency tasks with excellent cost efficiency. Model ID: claude-haiku-4-5-20250929
Fastest model optimized for high-volume, low-latency tasks with excellent cost efficiency. Model ID: claude-haiku-4-5-20250929
Released January 2025
Latest Generation
Both models represent Anthropic's most advanced AI technology with enhanced capabilities
Both models represent Anthropic's most advanced AI technology with enhanced capabilities
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Choosing the Right Model
Use Sonnet 4.5 For:
• Complex coding and software development
• Advanced reasoning and analysis
• Research and content creation
• Tasks requiring highest intelligence
• When quality matters more than speed
• Advanced reasoning and analysis
• Research and content creation
• Tasks requiring highest intelligence
• When quality matters more than speed
Use Haiku 4.5 For:
• High-volume API requests
• Real-time chat applications
• Quick content moderation
• Customer service automation
• When speed and cost efficiency matter
• Real-time chat applications
• Quick content moderation
• Customer service automation
• When speed and cost efficiency matter
Pro Tip
Use Haiku 4.5 for initial processing or filtering, then escalate to Sonnet 4.5 for complex cases - best of both worlds!
Getting Started in 4 Easy Steps
Get API Key
console.anthropic.com
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Choose Model
Sonnet or Haiku 4.5
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Integrate API
Python, JS, or REST
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Build & Scale
Deploy your app
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Model Capabilities Comparison
Sonnet 4.5: Intelligence
Superior reasoning, coding, and analysis. Best-in-class performance on complex tasks.
Haiku 4.5: Speed
Ultra-fast responses with excellent quality. Optimized for high-throughput applications.
Cost Efficiency
Haiku 4.5 offers the best price-to-performance ratio for volume tasks.
Vision Capabilities
Both models support image analysis and multimodal understanding.
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Quick API Integration
Python SDK
pip install anthropicUse model: "claude-sonnet-4-5-20250929" or "claude-haiku-4-5-20250929"
TypeScript/JavaScript
npm install @anthropic-ai/sdkFull SDK support with types for both models
REST API
POST to api.anthropic.com/v1/messages
Direct HTTP access with your API key
Direct HTTP access with your API key
Model Selection Strategy
Evaluate Task
Complexity & volume
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Try Haiku 4.5
Fast & cost-effective
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If Needed: Sonnet
Complex reasoning
Best Practices for Claude 4.5
- Start with Haiku 4.5 - Test if it meets your needs before using Sonnet (saves costs)
- Clear System Prompts - Define Claude's role, tone, and expected output format upfront
- Use XML Tags - Structure complex inputs: <document>content</document>
- Think Step-by-Step - For Sonnet 4.5, ask it to reason through complex problems
- Provide Examples - Few-shot learning dramatically improves output quality
- Set Max Tokens - Control response length for predictable costs and latency
- Monitor Token Usage - Both models return usage metrics in API responses
- Temperature Settings - Use 0.0-0.3 for deterministic tasks, 0.7-1.0 for creative work
- Hybrid Approach - Use Haiku for filtering, Sonnet for deep analysis
- Test Thoroughly - Try Workbench (console.anthropic.com) before production deployment
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Quick Reference Guide
Sonnet 4.5 Details
Model ID: claude-sonnet-4-5-20250929
Best For: Complex tasks, coding, research
Context: 200K tokens
Speed: Optimized for quality
Best For: Complex tasks, coding, research
Context: 200K tokens
Speed: Optimized for quality
Haiku 4.5 Details
Model ID: claude-haiku-4-5-20250929
Best For: Speed, volume, real-time apps
Context: 200K tokens
Speed: Ultra-fast responses
Best For: Speed, volume, real-time apps
Context: 200K tokens
Speed: Ultra-fast responses
Resources
API Docs: docs.anthropic.com
Console: console.anthropic.com
Support: support.anthropic.com
Status: status.anthropic.com
Console: console.anthropic.com
Support: support.anthropic.com
Status: status.anthropic.com
Ready to Build with Claude 4.5?
Choose Sonnet for intelligence, Haiku for speed - or use both together
Get Your API Key