Claude Sonnet 4.5

Claude Sonnet 4.5 represents a significant step forward in agentic AI design, built to handle long-horizon autonomous work that previous models couldn't sustain. The model can operate independently for over 30 hours while maintaining clarity, orchestrating tools and coordinating multiple agents to solve complex problems—a leap past the seven-hour capability of its predecessor. This extended operational endurance, combined with memory and context management features, lets the system tackle multi-step projects spanning hours or days, whether autonomously completing coding tasks, deploying cybersecurity agents that patch vulnerabilities before exploitation, or driving research from raw data into ready-to-go office files.

The model builds on Anthropic's lineage of reasoning-focused architectures, specifically optimized for real-world production use cases rather than narrow benchmarks. Enhanced domain knowledge in coding, finance, research, and cybersecurity shapes its practical strengths, making it the strongest option for building complex agents that need to use computers, reason through hard problems, and deliver actionable results. Checkpoint and rollback capabilities introduced alongside the model allow agents to save progress mid-task and recover instantly, enabling the sustained autonomy that defines its role in modern AI-assisted workflows.