Claude Opus 5.5
Claude Opus 5.5
Fable-level answers for less than the Opus it replaces. The new default.
Updated
The read
Opus 5.5 reset the top of this index. Anthropic says it performs at the level of Fable 5.1 while costing less than Opus 5, and the independent leaderboards agree: it tops the Artificial Analysis index and sits second on the human-preference arena. It keeps the million-token window and runs long agent loops without drifting. If you want one paid model and no further decisions this quarter, this is it.
Where it shines
- Highest score on the Artificial Analysis index as of October 2026
- Matches the Fable tier on long agentic work at under half its price
- A fast mode for interactive work, in research preview
Worth knowing first
- No free API tier, and the Claude apps offer it only on paid plans
- Fast mode costs double and is still a research preview
Index score
92.8
Provisional. This score is read from the product's public capability, not from the one-prompt rebuild the fully reviewed entries went through, so treat it as a placing rather than a verdict.
- Rank
- 01 of 73
- Builds
- LLMs
- Category
- Frontier
- Output
- Text, code and tool calls over an API
- Pricing
- Paid only
- Best for
- Coding, agents and knowledge work from one model
Scores are our own editorial judgement, weighted craft 55, speed 10, control 15 and value 20.
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