Claude Sonnet 4.5

Claude Sonnet 4.5 is Anthropic's most capable coding model to date, purpose-built for developers who need to reason through complex problems and orchestrate multi-step workflows. The model positions itself as the strongest option for building sophisticated AI agents, excelling at computer use tasks that require understanding and manipulating tools, applications, and codebases. This design philosophy extends beyond traditional text generation toward genuinely acting as an intelligent partner in software development and technical problem-solving.

The model launched alongside a suite of agent-focused tooling that reflects its intended use case: checkpoint-based state saving in Claude Code for rollback control, a native VS Code extension for tighter IDE integration, expanded context editing capabilities, and persistent memory features that let agents operate over longer conversations with greater complexity. File creation, code execution, and spreadsheet and document generation were brought directly into the Claude apps experience. These additions signal a model designed not just to answer questions, but to actively participate in ongoing development work alongside humans, handling the kind of extended, multi-file complexity that characterizes real-world engineering projects.