Claude Opus 4.5: Anthropic's Most Capable Coding Model Arrives

Anthropic has released Claude Opus 4.5, their most powerful model yet, delivering state-of-the-art performance on real-world software engineering tasks. Released on November 24, 2025, Opus 4.5 represents a significant leap forward for developers tackling complex, long-horizon coding challenges.

Benchmark Dominance

Claude Opus 4.5 has achieved the highest scores on SWE-bench Verified among frontier models, cementing its position as the leading AI for software engineering. The performance gains are substantial:

10.6% improvement over Sonnet 4.5 on Aider Polyglot benchmark
15% improvement on Terminal Bench for autonomous tasks
29% better performance than Sonnet 4.5 on Vending-Bench
Superior coding across 7 of 8 programming languages tested
Outperforms all human candidates on Anthropic's internal performance engineering exam

Built for Agentic Work

Opus 4.5 excels at autonomous, multi-step tasks that require sustained reasoning and complex coordination. The model demonstrates:

Enhanced handling of ambiguity and creative problem-solving
Improved performance in agentic workflows and computer use
Advanced tool-use capabilities for complex agent coordination
Significant token efficiency gains (48-76% fewer tokens than previous versions)

Developer Platform Updates

Alongside the model release, Anthropic introduced several powerful features:

New Effort Parameter

Developers can now balance speed versus capability with a new "effort parameter," allowing fine-tuned control over model behavior for different use cases.

Claude Code Improvements

Enhanced Plan Mode with clarifying questions for better task understanding
Desktop app now supports parallel sessions
Claude for Chrome extended to all Max users
Claude for Excel expanded to Team and Enterprise users

Platform Accessibility

Removed Opus-specific usage caps for Max/Team Premium users
Advanced context management and memory tools

Safety and Alignment

Anthropic describes Opus 4.5 as their most robustly aligned model to date, featuring:

Enhanced resistance to prompt injection attacks
Reduced concerning behaviors in evaluations
Improved safety across all deployment contexts

Pricing and Availability

Claude Opus 4.5 is available now at $5 per million input tokens and $25 per million output tokens. The model can be accessed via:

Claude API using model ID claude-opus-4-5-20251101
Claude apps and web interface
Amazon Bedrock
Google Vertex AI
Microsoft Azure

What This Means for Developers

Opus 4.5 represents the new frontier for AI-assisted software development. Its exceptional performance on long-horizon autonomous tasks makes it ideal for complex refactoring, large codebase navigation, and sophisticated development workflows. The improved token efficiency means developers get more capability while potentially reducing costs on complex tasks.

See It In Action

Want to see how Opus 4.5 compares to other models? Check out our code sample comparisons to see the differences in real coding tasks.

Claude Opus 4.5 is now available through the Claude API and all major cloud platforms, setting a new benchmark for AI-powered software engineering.