Claude——From AI Safety Lab to SWE-bench Champion, the Strongest Closed-Source Agent Choice
Claude is Anthropic's closed-source LLM family, known for Constitutional AI training, agent capabilities, and coding performance. In July 2026, Opus 5 scored 96% on SWE-bench Verified to claim the coding crown, while Fable 5 led general capability at 83% on LiveBench. Four tiers (Fable / Opus / Sonnet / Haiku) span $1–$10, making this the only family in the series with zero open weights.