Claude 3 Opus was the flagship of the Claude 3 family, launched on March 4, 2024 alongside the faster Claude 3 Sonnet and Claude 3 Haiku. It was the first Claude generation with vision support, shipped with a 200K-token context window, and outperformed GPT-4 on a wide range of benchmarks at launch — a moment that established Anthropic as a genuine frontier-lab rival rather than a safety-focused also-ran.

Opus was marketed on graduate-level reasoning: it scored 50.4% on GPQA Diamond and 33.0% on SWE-Bench Verified, both leading numbers for early 2024. It remained Anthropic's largest model for over a year, until the Claude 4 generation arrived in May 2025, and its three-tier Haiku/Sonnet/Opus naming scheme still structures the Claude lineup today.