Claude
Family Overview
Developer: Anthropic PBC, a public benefit corporation founded in 2021 by former OpenAI researchers including CEO Dario Amodei and President Daniela Amodei. The San Francisco-based AI safety and research company has raised over $10 billion from investors including Amazon, Google, and Menlo Ventures.
Philosophy: Claude's defining characteristic is Constitutional AI (CAI), a training methodology that uses explicit principles (a "constitution") to guide model behavior rather than relying solely on human feedback. This constitution draws from the UN Universal Declaration of Human Rights, trust and safety best practices, and diverse global perspectives. The approach emphasizes transparency, scalability, and interpretability while pursuing the company's core values of building AI that is helpful, harmless, and honest.
Key Strengths: Industry-leading context windows up to 1 million tokens with exceptional recall performance, state-of-the-art coding capabilities across all tiers, robust multimodal vision support, hybrid reasoning modes combining instant responses with extended thinking for complex problems, and built-in safety measures through Constitutional AI. Claude models excel at agentic workflows with sophisticated tool use, computer control, and multi-step autonomous operations lasting hours to days.
When to Choose Claude: Select this family for applications requiring extended context handling, complex agentic workflows with tool orchestration, mission-critical coding tasks, autonomous computer use, or use cases where safety alignment and transparency are priorities. The three-tier system (Haiku, Sonnet, Opus) provides clear trade-offs between cost, speed, and capability.
Platform & Access
Platform Name: Anthropic Console
URL: https://console.anthropic.com/
Platform Capabilities: The Console provides a comprehensive developer environment including Workbench for interactive API testing and prompt optimization, API key management with workspace segmentation for cost control, collaborative prompt sharing and version control, and official SDKs for Python, TypeScript/JavaScript, and Java (beta). Additional features include prompt caching with up to 90% cost savings, Message Batches API for 50% asynchronous processing discounts, token counting API, tool use for function calling, code execution environments, citations for source attribution, and beta Agent Skills for specialized tasks.
Access Model: API-only proprietary service. Claude models are closed-source with no open weights or architecture details publicly available. Anthropic explicitly protects model weights as part of their safety and security approach.
API Availability:
- Direct Anthropic API (159 countries)
- Amazon Bedrock (AWS regions)
- Google Cloud Vertex AI (GCP regions)
- Claude.ai web interface (95+ countries)
Pricing Model: Token-based pay-as-you-go pricing with separate rates for input and output tokens. Batch API provides 50% discounts, and prompt caching offers up to 90% savings on cached reads. Extended thinking tokens billed as output. Claude.ai subscriptions available separately (Pro, Max, Team, Enterprise custom pricing).
Models
Claude Haiku 4.5 (claude-haiku-4-5-20251001)
Fastest model with near-frontier intelligence
- Parameters: Undisclosed
- Context Window: 200,000 tokens (200K)
- Max Output: 64,000 tokens (64K)
- Multimodal: Text, vision (images, up to 20 per request)
- Knowledge Cutoff: February 2025
- License: Proprietary (API access only)
- Link: Model Card
- Release Date: October 15, 2025
Primary Use Cases:
- Sub-agent orchestration managing parallel AI workflows with 73.3% SWE-bench Verified performance
- Automated computer use tasks and GUI navigation where it surpasses larger models
- Real-time content moderation with immediate safety checks across high-volume streams
- Cost-effective large-scale financial document analysis with 4-5x faster processing than Sonnet
Agentic Capabilities:
- Tool Use / Function Calling: Excellent - parallel and sequential tool calling with improved orchestration
- Structured Output: JSON schema support with typed properties and nested structures
- Notable Features: First Haiku model with extended thinking mode (128K token budget), explicit context awareness tracking token usage, computer use for autonomous desktop interaction, matches Claude Sonnet 4 performance at one-third cost
Claude Sonnet 4.5 (claude-sonnet-4-5-20250929)
Smartest model for complex agents and coding
- Parameters: Undisclosed
- Context Window: 200,000 tokens standard; 1,000,000 tokens (1M) in beta
- Max Output: 64,000 tokens (64K)
- Multimodal: Text, advanced vision for photos, charts, graphs, technical diagrams, PDFs, scientific visualizations
- Knowledge Cutoff: July 2025
- License: Proprietary (API access only)
- Link: Model Card
- Release Date: September 29, 2025
Primary Use Cases:
- Autonomous cybersecurity with proactive vulnerability patching achieving 44% reduction in intake time
- Extended autonomous coding tasks maintaining focus for 30+ hours achieving 77.2% on SWE-bench Verified
- Browser automation handling complete workflows from competitive analysis to procurement to onboarding
- Complex litigation analysis synthesizing full briefing cycles into judicial opinion drafts
Agentic Capabilities:
- Tool Use / Function Calling: Excellent - enhanced tool orchestration with parallel and interleaved execution, speculative parallel tool calls
- Structured Output: Full JSON mode support with enhanced parameter handling
- Notable Features: State-of-the-art computer use (61.4% OSWorld benchmark), extended autonomous operation for 30+ hours, Memory tool (beta) for file-based state persistence, interleaved thinking (beta) enabling reasoning between tool calls, 0% error rate on internal code editing benchmarks
Claude Opus 4.1 (claude-opus-4-1-20250805)
Exceptional model for specialized reasoning tasks
- Parameters: Undisclosed
- Context Window: 200,000 tokens (200K)
- Max Output: 32,000 tokens (32K)
- Extended Thinking Window: 64,000 tokens for internal reasoning
- Multimodal: Text, vision (photos, charts, graphs, technical diagrams, PDFs, flowcharts, slides), multilingual
- Knowledge Cutoff: March 2025
- License: Proprietary (API access only)
- Link: Model Card
- Release Date: August 5, 2025
Primary Use Cases:
- Multi-file code refactoring across large codebases with precision debugging that pinpoints exact corrections without introducing bugs
- Hours-long independent research conducting autonomous investigation and cross-source synthesis simultaneously analyzing patent databases with academic papers and market reports
- Days-long engineering tasks maintaining coherence across thousands of steps with checkpoints for progress saving
- Advanced financial analysis from entry-level to predictive modeling with autonomous cybersecurity operations
Agentic Capabilities:
- Tool Use / Function Calling: Excellent - parallel tool use with multiple tools simultaneously, extended thinking with tool use (beta) alternating between reasoning and execution
- Structured Output: Full JSON mode and structured data generation support
- Notable Features: Long-horizon task execution working continuously for up to 7 hours independently, memory capabilities for continuity across sessions, state-of-the-art TAU-bench performance, hybrid reasoning with instant or extended thinking modes, ASL-3 safety level
Model Comparison Table
| Model | Context | Parameters | Knowledge Cutoff | Agentic Capabilities | Best For |
|---|---|---|---|---|---|
| Opus 4.1 | 200K | Undisclosed | March 2025 | ⭐⭐⭐⭐⭐ | Complex reasoning, multi-day tasks |
| Sonnet 4.5 | 200K-1M | Undisclosed | July 2025 | ⭐⭐⭐⭐⭐ | Agentic workflows, computer use |
| Haiku 4.5 | 200K | Undisclosed | February 2025 | ⭐⭐⭐⭐ | High-volume, low-latency, cost-efficiency |
Key Considerations
API Model Aliases: Use version-agnostic API aliases like claude-haiku-4-5 rather than dated identifiers for automatic updates to latest model versions, though dated identifiers ensure consistency for production systems.
Content Filters and Safety: Constitutional AI provides built-in safeguards with explicit ethical principles. Models demonstrate strong safety performance (98-99% harmless response rates) but maintain very low over-refusal rates (0.08% for Opus 4.1), balancing safety with usability.
Extended Thinking Costs: When using extended thinking mode for deeper reasoning, thinking tokens are billed as output tokens at standard output rates.
Free Tier Limitations: Claude.ai (chat) free tier users have access to Haiku and Sonnet models but not Opus models, which require paid subscriptions (Pro, Max, Team, or Enterprise).
Computer Use Considerations: Computer use capabilities are powerful but require careful implementation with appropriate safeguards, as models can interact with browsers and desktop environments with significant autonomy.
Resources
Official Documentation:
https://docs.anthropic.com/
API Reference:
https://docs.anthropic.com/en/api/
SDKs:
Claude.ai Chat Interface:
https://claude.ai/
Claude Code:
https://docs.claude.com/en/docs/claude-code
Responsible Scaling Policy:
https://www.anthropic.com/responsible-scaling-policy