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Claude Sonnet 4.5 Release - Claims Industry-Leading Coding Performance

Announced September 30, 2025 (JST)

Anthropic has released its latest AI model "Claude Sonnet 4.5". The company positions this model as "the world's best coding model", claiming significant performance improvements over previous models.

Target Audience

  • Intermediate engineers tracking latest AI development tool trends

Key Points

  1. Understand Claude Sonnet 4.5's key benchmark performance
  2. Learn about technical advances including 30-hour autonomous operation
  3. Review pricing, availability, and future roadmap

Key Benchmark Performance

SWE-bench Verified

On SWE-bench Verified, which measures real-world software engineering tasks, Claude Sonnet 4.5 scored 77.2%. In high-compute configurations, it reached 82.0%, claiming industry-leading numbers.

OSWorld

On the OSWorld benchmark evaluating PC operation capabilities, it achieved 61.4%. This represents a significant improvement from the previous model Claude Sonnet 4's 42.2%.

Key Technical Advances

Extended Autonomous Operation

The most significant feature is the ability to perform continuous autonomous work for over 30 hours. Early enterprise trials reported successful autonomous completion of tasks including:

  • Building database services
  • Acquiring domain names
  • Conducting SOC 2 audits
  • Developing complex multi-step applications

Computer Control Capabilities

The model can directly operate browsers, navigate websites, and input data into spreadsheets. This functionality will be provided through the "Claude for Chrome" extension, currently available to users on the Max plan waitlist.

Details: Enhanced Reasoning and Mathematical Capabilities ### AIME Performance On AIME, which tests math olympiad problems, the model used extended thinking with 64K reasoning tokens to achieve performance comparable to competing models. Experts in finance, law, medicine, and STEM fields have noted significant improvements in specialized knowledge and reasoning capabilities compared to the previous Opus 4.1.

Safety and Alignment

Anthropic describes this model as "the most aligned frontier model":

  • Significantly reduced problematic behaviors like excessive compliance, deception, and power-seeking
  • Improved resistance to prompt injection attacks
  • Released at AI Safety Level 3 (ASL-3)
  • Implemented filters to detect CBRN-related inputs/outputs

Claude Code 2.0

  • Checkpoint feature: Save work and instantly rollback to previous states
  • VS Code extension: Use Claude Code directly from IDE
  • Terminal Interface 2.0: Added prompt history search (Ctrl+r)

Claude Agent SDK

Rebranded from Claude Code SDK. Provided as an agent building tool capable of handling diverse tasks beyond coding.

Claude API

  • Context editing feature: Automatically clear old context
  • Memory tools: Store information outside context window to manage long-running tasks

Imagine with Claude - Limited-Time Experimental Feature

Available to Max subscribers for 5 days only (September 30 - October 3, 2025). Experience Claude generating software in real-time with no pre-defined functions or code.

Access URL: https://claude.ai/imagine

Pricing and Availability

Pricing remains unchanged from Claude Sonnet 4:

ItemPrice
Input$3/million tokens
Output$15/million tokens

Available platforms: Claude API, Amazon Bedrock, Google Cloud Vertex AI, OpenRouter, Cursor, GitHub Copilot

Available immediately on major platforms from announcement day.

Market Impact

Considering the previous Sonnet 4 was announced in late May 2025, this major upgrade in just 4 months demonstrates rapid development pace. According to Anthropic insiders, subscription service run rate exceeded $5 billion as of August.

Reports indicate Apple and Meta are using Claude models internally, accelerating enterprise market adoption.

Next Steps

This article is based on publicly available information as of September 30, 2025.