Claude 3.5 Sonnet vs Claude Sonnet 4

Claude 3.5 Sonnet

Anthropic

Claude 3.5 Sonnet, updated by Anthropic in October 2024 (originally released June 2024), is a large language model from the Claude 3.5 family that delivered strong performance in coding, reasoning, and instruction-following at its release. It supports a 200K token context window, 8K maximum output tokens, and native image understanding including screenshot analysis and document comprehension. Claude 3.5 Sonnet targets general-purpose development tasks, document analysis, and applications requiring reliable instruction following with visual input support.

Claude Sonnet 4

Anthropic

Claude Sonnet 4, released by Anthropic in May 2025, is a large language model from the Claude 4 family that delivers a balance of performance and efficiency for coding, reasoning, and analytical tasks. It features a 200K token context window (extendable to 1M tokens in beta), 64K maximum output tokens, native image understanding, and extended thinking support. Sonnet 4 targets development workflows, document analysis, and applications that benefit from the performance characteristics of the Claude 4 generation.