Claude Sonnet 5.5 just launched, running over 30% faster than Sonnet 5 while needing far fewer tokens to complete the same tasks. It's the second model in the Claude 5.5 family, following Opus 5.5 which launched on September 22nd. Claude Haiku 5.5 is expected to join the lineup in the coming weeks. Sonnet 5.5 is positioned as a faster, cheaper complement to Opus 5.5, built for well scoped everyday tasks like fixing bugs, writing documents, and polishing slides and spreadsheets. On several benchmarks, Sonnet 5.5 at low or medium effort beats Sonnet 5's best score for roughly a tenth of the cost. Some users have also reported it outperforming Opus 5.5 on certain agentic coding and terminal benchmarks. Pricing remains unchanged from Sonnet 5, and the model is available everywhere starting today.