Claude Sonnet 4.5

Claude Sonnet 4.5 positions itself as the definitive model for software development and autonomous agentic work. Its architecture is purpose-built for extended operation, maintaining task continuity across sessions while delivering state-of-the-art performance on coding benchmarks such as SWE-bench Verified. The model demonstrates particular strength in tool orchestration, speculative parallel execution, and efficient context and memory management. With enhanced awareness of token usage across tool calls, it handles multi-context and long-running workflows that require sustained reasoning, making it well-suited for complex agents that need to operate independently over extended periods.

The model targets professional developers and organizations building sophisticated AI agents for software engineering, cybersecurity, financial analysis, and research domains. Beyond raw capability, Sonnet 4.5 ships with a developer toolkit built from the same components Anthropic uses internally for Claude Code, including checkpoint management, memory tools, and context editing features that let agents handle greater complexity. Its design emphasis on specification adherence, code security, and fact-based progress tracking reflects a shift toward models that can take ownership of substantial workflows rather than simply answering individual prompts.

Amazon Bedrockanthropic.claude-sonnet-4-5-20250929-v1:0claude-sonnet

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Quick Info

Provider: Amazon Bedrock
Model key: anthropic.claude-sonnet-4-5-20250929-v1:0
Release date: Sep 29, 2025
Last updated: Sep 29, 2025
Knowledge cutoff: 2025-07-31
Input modalities
Output modalities
Capabilities

Cost

Input token cost: $3.00
Output token cost: $15.00

Limits

Output tokens: 64,000 tokens
Context window: 200,000 tokens

Transparent token rates

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Rates are shown per one million tokens. Combined means one million input plus one million output tokens.

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Latest news about Claude Sonnet 4.5

Amazon Bedrock

Coverage

Amazon, following Google and Microsoft, reassures customers that Anthropic's AI models will remain available for non-defense related workloads despite recent federal restrictions.

Amazon Bedrock

Coverage

Amazon Web Services announces that Anthropic’s Claude Opus 4.6, Claude Sonnet 4.6, Claude Opus 4.5, Claude Sonnet 4.5, and Claude Haiku 4.5 are now available through Amazon Bedrock with global cross-Region inference for customers in the Middle East, including UAE (me-central-1) and Bahrain (me-south-1). The feature rou

Amazon Bedrock

Official sourceRelease Notes

Discover more about what's new at AWS with Amazon Bedrock increases default quotas for Anthropic’s Claude Sonnet 4.5 model in AWS GovCloud (US)

Amazon Bedrock

CoverageBenchmark

CodeRabbit's October 3, 2025 benchmark evaluation compares Claude Sonnet 4.5 against Sonnet 4 and Opus 4.1 across 25 difficult real-world pull requests with known critical bugs. The vendor finds Sonnet 4.5 delivers coverage closer to Opus 4.1, with 41.5% of its comments rated as "Important" versus 35.3% for Sonnet 4, c The analysis characterizes Sonnet 4.5 as a pragmatic price-versus-performance sweet spot, offering near-Opus-level code review quality at Sonnet pricing. However, the reviewer notes the model "hedges" and uses "conditional" warning framing more frequently, which can make its comments harder to parse for some users seek

Amazon Bedrock

CoverageBenchmark

Cirra AI's technical analysis details Claude Sonnet 4.5's release on September 29, 2025, and describes Anthropic's positioning of it as 'the best model in the world for agents, coding, and computer use.' It highlights a 200,000-token context window (up to 64K output), hybrid reasoning with an 'extended thinking' mode f Beyond marketing copy, the article dives into benchmark behavior and real-world use cases to characterize where Sonnet 4.5 improves over predecessors. Although it is a third-party analysis rather than official Anthropic or AWS documentation, its sourcing is grounded in Anthropic's launch materials and corroborates Sonn

Amazon Bedrock

Official sourceRelease Notes

Discover more about what's new at AWS with Amazon Bedrock Reserved Tier available now for Claude Sonnet 4.5 in AWS GovCloud (US-West)