Claude Opus 5.5
Anthropic's most capable Opus model, cheaper to run than Opus 5
Paid
Reasoning
1000000
context tokens
Undisclosed
parameters
Proprietary
license
Sep 2026
released
Anthropic released Claude Opus 5.5 on September 22, 2026, keeping the 1 million token context window of Claude Opus 5 while matching Claude Fable 5.1 on most of Anthropic’s benchmark suite. The main change is cost: Anthropic says Opus 5.5 runs roughly 40% cheaper than Opus 5 on typical workloads, making it a straight upgrade for teams already on the Opus tier rather than a separate product line.
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