Claude 4

Claude 4 encompasses two distinct models from Anthropic: Claude Opus 4, the highest-capability model in the family designed for demanding analytical and engineering tasks, and Claude Sonnet 4, a balanced model optimized for everyday performance and efficiency. Both models feature extended context windows that allow processing of large codebases, lengthy documents, and complex multi-turn conversations in a single session. Claude 4 supports agentic use cases where the model can plan, execute, and iterate on multi-step tasks with access to tools and external resources. The models are accessible through the Claude.ai web interface, mobile applications, and the Anthropic API for developers building applications. Claude 4 is used across software engineering, research, legal analysis, content production, and enterprise automation. Developers use Opus 4 for complex code generation, debugging, architectural review, and test writing across dozens of programming languages. Research teams use it to synthesize large volumes of source material and produce structured analysis. Legal and compliance professionals apply it to contract review and document summarization. Businesses building AI-powered products integrate Claude 4 through the API to power customer-facing agents, internal automation tools, and document processing pipelines. Claude Sonnet 4 serves the same workflows at a faster processing speed and lower API cost, making it the default choice for high-volume applications. Claude 4 is technically distinguished by its performance on software engineering benchmarks, where Opus 4 scores at or near the top of published evaluations at the time of its release, and by Anthropic's focus on model safety and alignment — the models are trained with Constitutional AI methods intended to reduce harmful outputs. The free tier on Claude.ai provides access to Sonnet 4 with usage limits, and the Pro plan at $20 per month provides higher message limits and access to Opus 4. API pricing is usage-based and varies by model and token volume. A key practical consideration is that the most capable model, Opus 4, is more computationally intensive and carries a higher API cost per token than Sonnet 4, which affects cost planning for high-volume deployments.