Claude Sonnet 4vsClaude 3.5 Sonnet

Claude Sonnet 4 is Anthropic's balanced mid-tier model, offering an excellent combination of intelligence, speed, and cost-effectiveness. It ranks among the top 5 models globally on arena benchmarks while being significantly more affordable than Opus 4. With a 200K token context window, Sonnet 4 handles long documents and complex codebases with ease. The model excels at coding tasks (strong SWE-bench performance), long-form writing, document analysis, and structured data extraction. Its extended thinking capabilities allow it to tackle complex problems while maintaining fast response times for everyday tasks. Sonnet 4 is the most popular Claude model for production applications, offering the best price-to-performance ratio in Anthropic's lineup. It supports tool use, vision capabilities, and works seamlessly in agentic workflows.

Claude 3.5 Sonnet was Anthropic's previous generation balanced model that set new industry benchmarks when released. It demonstrated that mid-tier models could compete with and even surpass flagship models from competitors on coding, reasoning, and analysis tasks. The model featured a 200K token context window and introduced Anthropic's Artifacts feature for interactive code execution. Claude 3.5 Sonnet became one of the most popular models for professional developers and enterprises, known for its excellent code generation, careful instruction following, and reduced hallucination rates. While now succeeded by Claude Sonnet 4, it remains widely deployed in production systems and continues to offer strong performance at its price point. It was instrumental in establishing Anthropic as a serious competitor to OpenAI.