Claude Sonnet 4.6 is an AI model released by Anthropic on Feb 17 2026, 12 days after Claude Opus 4.6. It is the 18th tracked release from Anthropic out of 19 total.
On published benchmarks, it scores 89.9% on GPQA Diamond (graduate-level science reasoning), 79.6% on SWE-Bench Verified (real-world software engineering).
About Anthropic: AI safety company building the Claude family of models. Founded in 2021 by former OpenAI researchers.