Claude Opus 4
Released
Claude Opus 4 is an AI model released by Anthropic on Thursday, May 22 2025, the same day as Claude Sonnet 4. Benchmark results (shown below) cover BullshitBench v2, SWE-Bench Verified, and GPQA Diamond.
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About
Claude Opus 4 arrived May 22, 2025 together with Claude Sonnet 4, reviving the Opus tier after more than a year and marking Anthropic's pivot to long-horizon agentic work. It was pitched at sustained, multi-hour coding sessions — refactoring across large codebases, running in agent harnesses, and using tools in extended loops — rather than single-shot chat answers.
It posted 79.6% on GPQA Diamond and 72.5% on SWE-Bench Verified, roughly ten points above Claude 3.7 Sonnet on software engineering. Claude Opus 4.1 followed on August 5, 2025 as an incremental refinement, and the Opus line has since been Anthropic's flagship tier through Opus 4.5 and beyond.
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Frequently asked questions
Claude Opus 4 was released by Anthropic on Thursday, May 22 2025.
Claude Opus 4 was built by Anthropic. AI safety company building the Claude family of models. Founded in 2021 by former OpenAI researchers.
Claude Opus 4 reports 3 tracked benchmark scores — BullshitBench v2: 34%; SWE-Bench Verified: 72.5%; GPQA Diamond: 79.6%. Scores are the figures published at release by Anthropic.
No. Claude Opus 4 is a proprietary model. The weights are not published — it is available only through the provider's own API, apps, or partner platforms.
Anthropic's previous tracked release was Claude Sonnet 4 on May 22 2025. It was followed by Claude Opus 4.1 on Aug 5 2025.