Claude Sonnet 5.5

Claude Sonnet 5.5 API: Anthropic's newest Sonnet, the best combination of speed and intelligence, 30%+ faster than Sonnet 5 at the same price

Claude Sonnet 5.5 is the newest model in Anthropic's Sonnet line and the successor to Claude Sonnet 5, which Anthropic calls the best combination of speed and intelligence. It keeps Sonnet 5's price ($2 input / $10 output per million tokens, $0.20 cache reads) and foundation (a 1M-token context window, up to 128K output tokens per request, the same tokenizer, image input, tool use and prompt caching), while generating output more than 30% faster and costing up to 30% less per task because it uses fewer tokens and tool calls. It scores 70.6% on Terminal-Bench 4.0 and is strongest at well-scoped everyday work: building features, fixing bugs, and producing polished documents, slides and spreadsheets. Thinking is always on, with five effort levels (low to max; default high). NezhaGate is integrating it now: leave your email and we will tell you the day it goes live.