Claude Opus 5.5
Rank of 2701from #1
Known for
The hardest coding and computer work, without paying Fable prices.
The first model in Anthropic's new 5.5 family, out on 22 September 2026. Anthropic says it works at the level of Fable 5.1 on most jobs and costs 40% less to run than Opus 5. Its 89.9% on SWE-bench Pro is the highest score on this board.
What it does8
- Context up to 1M tokens
- Adaptive thinking with effort control, up to xhigh
- $4 / $20 per million tokens, against Opus 5's $5 / $25
- Cache reads at $0.20 per million
- Text and image in, text out
- Checked before release by Frontier Design and METR
- Best result Anthropic has recorded on its own alignment audit
- Safeguards matching Fable 5.1's, for biology and cyber work
From Claude Opus 5.5’s own site. Not used for ranking.
82index score · LLMs
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Compared with everyone else on this board.
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